Major method-specific differences in the measurement of intact parathyroid hormone: studies in patients with and without chronic renal failure.

BACKGROUND: Following the introduction of two-site immunometric assays for parathyroid hormone (PTH), the expectation of good inter-assay agreement has not been fulfilled. The reasons for this may include differences in standardization as well as fragment recognition between the assays. METHODS: PTH values for healthy individuals, patients with renal failure and patients with normal renal function and elevated parathyroid hormone (hPTH) were compared using two commercial two-site immunochemiluminometric assays (Bayer Magic-lite and DPC Immulite 2000). RESULTS: Immulite results had a mean value 50.4% greater than the corresponding Magic-lite values for the whole study population with individual values ranging from 17.5% below to 118.3% above the corresponding Magic-lite value. There was no significant difference in inter-assay bias between patients with renal failure and those with normal renal function, suggesting that variable cross-reactivity with circulating disease-specific PTH fragments was not the primary cause of the observed discrepancy. Cross-reactivity with the synthetic fragment hPTH (7-84) was 34+/-5% for Magic-lite and 62+/-2% for Immulite. We also studied the stability of synthetic hPTH on storage. CONCLUSION: The instability of synthetic hPTH over extended storage periods may affect primary standard material. The consistent inter-assay differences and the over-recovery observed in external quality assessment programmes for the Immulite assay may have best been explained by differences in calibration and the relative cross-reactivities and/or kinetics of the two assay systems for specific parathyroid fragments.

A randomized clinical trial comparing oral alendronate and intravenous pamidronate for the treatment of Paget's disease of bone.

Second and third generation bisphosphonates are the treatment of choice for Paget's disease of bone. These drugs are more effective than calcitonin and etidronate, but there have been no head to head, randomized controlled trials comparing potent bisphosphonates. We conducted a 2-year, randomized, open-label trial comparing oral alendronate and intravenous pamidronate in 72 subjects with Paget's disease. Randomization was stratified according to baseline plasma total alkaline phosphatase (ALP) and previous bisphosphonate treatment (yes or no). All previously treated patients had received pamidronate but not alendronate. Assigned treatments were pamidronate (60 mg) every 3 months as a single infusion or alendronate (40 mg) daily in 3-month blocks, continued until biochemical remission (defined as both ALP and urine deoxypyridinoline (DPD)/creatinine ratio in the reference range) or a clear plateau effect was observed. At 1 year, nonresponders to pamidronate were crossed over to alendronate treatment. At 1 year, 31/36 (86%) subjects randomized to alendronate achieved biochemical remission compared with 21/36 (56%) for pamidronate (P = 0.017). There was a significantly greater reduction in ALP (P < 0.001) and DPD/creatinine ratio (P < 0.001) for alendronate compared with pamidronate treatment. In previously untreated patients, alendronate resulted in remission in 20/22 (91%) subjects compared with 19/22 (86%) of pamidronate-treated subjects, which was not significantly different; however, alendronate resulted in a significantly greater reduction in ALP (P = 0.014) and DPD/creatinine ratio (P < 0.001). In previously treated patients, alendronate resulted in remission in 11/14 (79%) subjects compared with 2/14 (14%) for pamidronate (P < 0.001), with a significantly (P < 0.001) greater reduction in both ALP and DPD/creatinine ratio. Of subjects crossed over from pamidronate to alendronate, 10/14 (71%) achieved remission, including 9/11 (82%) previously treated patients. We conclude that, in patients with previously untreated Paget's disease of bone, alendronate and pamidronate have similar efficacy in achieving biochemical remission. In patients previously treated with pamidronate, alendronate is more effective.

A randomized trial comparing hormone replacement therapy (HRT) and HRT plus calcitriol in the treatment of postmenopausal osteoporosis with vertebral fractures: benefit of the combination on total body and hip density.

We report a prospective, randomized, multicenter, open-label 2-year trial of 81 postmenopausal women aged 53-79 years with at least one minimal-trauma vertebral fracture (VF) and low (T-score below - 2) lumbar bone mineral density (BMD). Group HRT received piperazine estrone sulfate (PES) 0.625 - 1.25 mg/d +/- medroxyprogesterone acetate (MPA) 2.5 - 5 mg/d; group HRT/D received HRT plus calcitriol 0.25 microg bd. All with a baseline dietary calcium (Ca) of < 1 g/ d received Ca carbonate 0.6 g nocte. Final data were on 66 - 70 patients. On HRT/D, significant (P < 0.001) BMD increases from baseline by DXA were at total body - head, trochanter, Ward's, total hip, intertrochanter and femoral shaft (% group mean delta 4.2, 6.1, 9.3, 3.7, 3.3 and 3.3%, respectively). On HRT, at these 6 sites, significant deltaS were restricted to the trochanter and Wards. Significant advantages of HRT/D over HRT were in BMD of total body (- head), total hip and trochanter (all P = 0.01). The differences in mean delta at these sites were 1.3, 2.6 and 3.9%. At the following, both groups improved significantly -lumbar spine (AP and lateral), forearm shaft and ultradistal tibia/fibula. The weightbearing, site - specific benefits of the combination associated with significant suppression of parathyroid hormone-suggest a beneficial effect on cortical bone. Suppression of bone turnover was significantly greater on HRT/D (serum osteocalcin P = 0.024 and urinary hydroxyproline/creatinine ratio P = 0.035). There was no significant difference in the number of patients who developed fresh VFs during the trial (HRT 8/36, 22%; HRT/D 4/34, 12% - intention to treat); likewise in the number who developed incident nonvertebral fractures. This is the first study comparing the 2 treatments in a fracture population. The results indicate a significant benefit of calcitriol combined with HRT on total body BMD and on BMD at the hip, the major site of osteoporotic fracture.

Bone density changes in Paget's disease 2 years after iv pamidronate: profound, sustained increases in pagetic bone with severity-related loss in forearm nonpagetic cortical bone.

Bone mineral density (BMD) was measured at three sites (forearm, spine, and hip) using dual X-ray and single-photon absorptiometry in 68 patients with Paget's disease before and after treatment with iv pamidronate. Patients were treated according to the severity of their disease; the mild category (Group I, hydroxyproline excretion (Hyp(E)) <5.0 micromol/L GF) received 120 mg, the moderate category (Group II, Hyp(E) 5.0-9.99 micromol/GF) 180 mg, and the severe category (Group III, > or = 10.0 micromol/GF) 240 mg. Group I was followed for 1 year, and both Groups II and III for 2 years. At the lumbar spine in pagetic bone there were no differences between groups in early responses, with a profound increase 6 months after treatment 20.5 +/- 2.0% above baseline values to 1.403 +/- 0.063 g/cm(2) (mean +/- SEM)(P < 0.001). This increase in BMD was sustained to 2 years (1.355 +/- 0.078 g/cm(2), P < 0.001) and was 15.0 +/- 2.2% above baseline values. The pagetic total hip BMD increased after treatment in all groups, with a mean rise of 10.4 +/- 1.4% at 1 year to 1.505 +/- 0.083 g/cm(2) (P < 0.01). At the pagetic femoral neck the response was similar, with a peak significant rise at 1 year of 10.7 +/- 1.7% to 1.403 +/- 0.097 g/cm(2) (P < 0.01). In nonpagetic spinal bone there were no differences between the group responses, with a combined mean increase of 4.3 +/- 0.7% at 1 year to 0.999 +/- 0.027 g/cm(2) (P < 0.01). In both Groups II and III the increase in BMD was significantly higher than baseline values at 1 and 2 years (P < 0.01). In the nonpagetic total hip BMD remained unchanged over the 2-year period and likewise, there were no significant changes from baseline at the nonpagetic femoral neck site. In the nonpagetic forearm we found a significant loss in BMD at the ultradistal (mainly trabecular), midregion (80% cortical), and proximal shaft (95% cortical) sites in Group III, persisting to 2 years at the latter two sites. The increase in bone density in pagetic bone, persisting at least 2 years, provides a new modality of assessment of the response of pagetic bone to treatment and suggests a mechanism for the reduction in fracture risk in such bone after effective bisphosphonate treatment. Severity-dependent nonpagetic forearm bone loss, persisting to 2 years at cortical sites, suggests a potential drug-induced fracture risk at the forearm and possibly elsewhere in the absence of appropriate preventive cotreatment.

A randomized trial of sodium fluoride (60 mg) +/- estrogen in postmenopausal osteoporotic vertebral fractures: increased vertebral fractures and peripheral bone loss with sodium fluoride; concurrent estrogen prevents peripheral loss, but not vertebral fractures.

Postmenopausal Caucasian women aged less than 80 years (n = 99) with one or more atraumatic vertebral fracture and no hip fractures, were treated by cyclical administration of enteric coated sodium fluoride (NaF) or no NaF for 27 months, with precautions to prevent excessive stimulation of bone turnover. In the first study 65 women, unexposed to estrogen (-E study), age 70.8 +/- 0.8 years (mean +/- SEM) were all treated with calcium (Ca) 1.0-1.2 g daily and ergocalciferol (D) 0.25 mg per 25 kg once weekly and were randomly assigned to cyclical NaF (6 months on, 3 months off, initial dose 60 mg/day; group F CaD, n = 34) or no NaF (group CaD, n = 31). In the second study 34 patients, age 65.5 +/- 1.2 years, on hormone replacement therapy (E) at baseline, had this standardized, and were all treated with Ca and D and similarly randomized (FE CaD, n = 17; E CaD, n = 17) (+E study). The patients were stratified according to E status and subsequently assigned randomly to +/- NaF. Seventy-five patients completed the trial. Both groups treated with NaF showed an increase in lumbar spinal density (by DXA) above baseline by 27 months: FE CaD + 16.2% and F CaD +9.3% (both p = 0.0001). In neither group CaD nor E CaD did lumbar spinal density increase. Peripheral bone loss occurred at most sites in the F CaD group at 27 months: tibia/fibula shaft -7.3% (p = 0.005); femoral shaft -7.1% (p = 0.004); distal forearm -4.0% (p=0.004); total hip -4.1% (p = 0.003); and femoral neck -3.5% (p = 0.006). No significant loss occurred in group FE CaD. Differences between the two NaF groups were greatest at the total hip at 27 months but were not significant [p < 0.05; in view of the multiple bone mineral density (BMD) sites, an alpha of 0.01 was employed to denote significance in BMD changes throughout this paper]. Using Cox's proportional hazards model, in the -E study there were significantly more patients with first fresh vertebral fractures in those treated with NaF than in those not so treated (RR = 24.2, p = 0.008, 95% CI 2.3-255). Patients developing first fresh fractures in the first 9 months were markedly different between groups: -23% of F CaD, 0 of CaD, 29% of FE CaD and 0 of E CaD. The incidence of incomplete (stress) fractures was similar in the two NaF-treated groups. Complete nonvertebral fractures did not occur in the two +E groups; there were no differences between groups F CaD and CaD. Baseline BMD (spine and femoral neck) was related to incident vertebral fractures in the control groups (no NaF), but not in the two NaF groups. Our results and a literature review indicate that fluoride salts, if used, should be at low dosage, with pretreatment and co-treatment with a bone resorption inhibitor.

Bisphosphonate therapy for Paget's disease in a patient with hypoparathyroidism: profound hypocalcemia, rapid response, and prolonged remission.

Bisphosphonate treatment for severe Paget's disease leads to hypocalcemia followed by a secondary hyperparathyroid response to restore normocalcemia. A case is presented of a 60-year-old woman with polyostotic Paget's disease and postsurgical hypoparathyroidism. In 1993 her Paget's disease--alkaline phosphatase (ALP), 1260 U/liter (35-135 U/liter), and fasting urinary hydroxyproline excretion, 13.7 micromol/liter GF (0.4-1.9 micromol/liter)--was treated with intravenous pamidronate. Symptomatic hypocalcemia followed the first 60-mg dose, requiring large doses of calcium supplementation and calcitriol. Pamidronate therapy to a total dose of 360 mg was followed by rapid and prolonged remission with indices of bone turnover in the normal range within 2 months and persisting for at least 19 months after treatment. In 1999 relapse of Paget's disease--ALP, 511 U/liter (35-135 U/liter), and fasting urinary deoxypyridinoline/creatinine 53.1 micromol/mol (5-27 micromol/mol)--was treated with alendronate, 10 mg daily. Symptomatic hypocalcemia occurred again, requiring increased calcium and calcitriol therapy. Indices of bone turnover were within the normal range 9 weeks after the start of therapy. These responses were significantly more rapid and sustained than those observed in euparathyroid subjects. This case suggests that the lack of parathyroid response may modify the response to bisphosphonates by: (a) increasing intrinsic uptake of bisphosphonate into the pagetic skeleton, allowing response to a smaller dose; (b) increasing duration and severity of hypocalcemia after bisphosphonate therapy; and (c) removing the hyperparathyroid drive to reactivation of pagetic osteoclasts, leading to a prolonged remission. These observations have implications for optimizing bisphosphonate therapy both in Paget's disease and in osteoporosis.

Calcium absorption in postmenopausal osteoporosis: benefit of HRT plus calcitriol, but not HRT alone, in both malabsorbers and normal absorbers.

In a randomized trial involving 71 postmenopausal osteoporotic women with vertebral compression fractures, radiocalcium absorption studies using the (45)Ca single isotope method (alpha) were performed at baseline and after 8 months of treatment with either continuous combined hormone replacement therapy (HRT, as piperazine estrone sulfate 0.625-0.937 mg daily +/- medroxyprogesterone acetate 2.5 mg daily depending on uterine status) or HRT plus calcitriol 0. 25 microg twice daily. A calcium supplement of 600 mg nocte was given to only those women who had a daily calcium intake of less than 1 g per day at baseline, as assessed by recalled dietary intake. There was a significant decrease [0.74 (+/- 0.35 SD) to 0.58 (+/- 0. 22), Dalpha = -0.17 (+/- 0.26), p<0.0005] in alpha at 8 months compared with baseline in the HRT-treated group, but a significant increase [0.68 (+/- 0.31) to 0.84 (+/- 0.27), Dalpha = +0.16 (+/- 0. 30), p<0.003] in the HRT-plus-calcitriol treated patients, resulting in alpha being significantly higher after 8 months in the latter group than in the HRT-only group. Although 72% of the patients had been supplemented with calcium between the first and second studies, separate analyses revealed that the change in calcium intake had not affected the result. Further breakdown of the groups into baseline 'normal' absorbers (alpha >/=0.55) and 'malabsorbers' (alpha <0.55) revealed that alpha decreased with HRT treatment only in the normal absorbers, and remained stable in the malabsorbers. Conversely, following HRT plus calcitriol treatment, alpha increased only in the malabsorbers, the normal absorbers in this group remaining unchanged. In conclusion, our data show that HRT, of the type and dose used in this study, did not produce an increase in absorption efficiency; it was in fact associated with a fall. Increased absorption efficiency cannot be achieved unless calcitriol is used concurrently, and then only in patients with malabsorption. Calcitriol also had a significant effect in normal absorbers in that it prevented the decline in alpha seen with HRT alone, and thus should be considered in all patients with postmenopausal osteoporosis treated with HRT.

Thirty cases of concurrent Paget's disease and primary hyperparathyroidism: sex distribution, histomorphometry, and prediction of the skeletal response to parathyroidectomy.

Studies of the effect of parathyroidectomy (PTX) on bone turnover in patients with the combination of primary hyperparathyroidism (PHPT) and Paget's disease (PD) are largely limited to case reports. The etiology of the combination is disputed. We report 30 patients and their biochemical (n = 17) and histomorphometric (n = 4) responses to PTX in 18. All 18 patients except one had a post-PTX fall in plasma alkaline phosphatase (pAP). There was a significant positive correlation between the degree of post-PTX fall in pAP and both the preoperative plasma total corrected calcium (CaC) (P < 0.01) and serum ionized calcium (P < 0.05). For the patients with CaC levels >3.0 mmol/liter, the mean % fall in pAP was 68% of pretreatment (to 32%). For those with CaC levels >/=2.68 mmol/liter the fall in pAP was >18%. Of 12 literature cases treated by PTX and followed up, 11 had a postoperative fall in pAP (range 6-83%). Pretreatment bone biopsies (n = 6) could not be distinguished from uncomplicated PD. No significant histomorphometric changes were documented postoperatively in the four patients studied; however, % fibrotic surfaces declined in each of the four. Of the 18 patients, only one had radiologic subperiosteal erosions preoperatively; none had clinical tetany postoperatively-thus distinguishing this combination of diseases from severe PHPT bone disease-a situation easily biochemically confused with this combination. The sex distribution of 2.75:1 F/M in this series resembles reported ratios in pure PHPT of 2.37:1, unlike the ratios found in pure PD (0.49-1.01:1). The prevalence of PHPT in PD is 2.2-6.0% (mean 4.4%) in 1836 patients. In our series, 73% of patients with both diseases were females >60 years of age. In population studies >60 years, PHPT was present in 3% of women and 1% of men. Hypercalcemia in PD is frequently attributed to immobilization. As part of this study, we examined 184 patients referred with PD for the existence of, and cause of hypercalcemia. Of this group, 21 were hypercalcemic, 19 (90%) of whom had PHPT; none had immobilization hypercalcemia. In patients with both disorders, the indications for PTX should include the potential post-PTX improvement in pagetic biochemistry and symptoms. The sex distribution (resembling pure PHPT) and the similar prevalence of PHPT in Paget's, and in the elderly population, support the likelihood, in most cases, that these two common diseases are associated by chance.

Paget's disease: acquired resistance to one aminobisphosphonate with retained response to another.

Twenty-five years after the first paper on etidronate in Paget's disease, there are few published papers that address bisphosphonate resistance as a specific clinical phenomenon. We report our data from two studies. Study 1 is a retrospective study of 20 patients with moderate to severe disease who were treated with intravenous (iv) pamidronate (221 +/- 18 mg [SEM]; range 60-360 mg), and after biochemical remission and relapse were retreated with generally larger iv dosage (293 +/- 28 mg; range 180-600 mg). The nadir bone turnover values were similar: plasma alkaline phosphatase (pAP) in 20 patients was 243 +/- 40 IU/l (mean +/- SEM) after the first course, and 267 +/- 44 IU/l after the second (reference range [RR] 35-135 IU/l). Likewise, fasting urinary hydroxyproline excretion (HypE) in 14 of the 20 patients was 4.5 +/- 1.1 micromol/LGF and 4.1 +/- 0.9 micromol/LGF, respectively (RR 0.40-1.92 micromol/LGF). However the minimum duration of biochemical remission was significantly shorter after the second course-10.9 +/- 1.7 months (first) and 5.6 +/- 0.9 months (second) (p < 0.03; Friedman's ANOVA n = 17). A subgroup of 10 patients who were followed for three courses showed a significantly higher pAP nadir in the third course. Study 2 is a prospective study of 40 patients, 23 previously untreated (NILPREV) and 17 previously treated with iv pamidronate (PAMPREV) and in biochemical relapse, who were randomly allocated to either oral alendronate 40 mg daily in 3 month units, or iv pamidronate 60 mg every 3 months. Treatment was continued until pAP and fasting urinary deoxypyridinoline/creatinine (Dpy/Cr) ratios (RR 5-27 micromol/mol) were both in the reference range, or a clear plateau in each marker developed. At baseline, there were no significant differences in either marker between the two NILPREV groups and between the two PAMPREV groups. Using log-transformed data, in NILPREV the pAP reductions were significant and similar over the first 6 months. However, although each Dpy/Cr reduction was also significant, the difference in responses favored alendronate (p < 0.015). In PAMPREV both markers showed no significant response to pamidronate; comparison showed a significantly greater response to alendronate (pAP p < 0.02; Dpy/Cr p < 0.002). Using two-way ANOVA, the pAP responses to alendronate in NILPREV and PAMPREV were similar and those to pamidronate were different (p = 0.034). The percentage of patients with both markers in the RR at 6 months or earlier were identical in NILPREV patients: alendronate 87% and pamidronate 87%. However in PAMPREV they were different: alendronate 83% and pamidronate 0% (p = 0.003). These data indicate: 1) patients treated with the same aminobisphosphonates for two courses show similar nadir values of bone turnover markers but a shorter remission time after the second course. In a third course the nadirs are significantly higher; and 2) in the alendronate/pamidronate comparison, NILPREV and PAMPREV patients showed similar pAP responses to alendronate, but significantly different responses to pamidronate. Thus, patients showing acquired partial resistance to one aminobisphosphonate (usually after two or more previous courses) are still capable of remission after exposure to another compound of the same class.

Prevention of appendicular bone loss in Paget's disease following treatment with intravenous pamidronate disodium.

It has been shown previously that intravenous pamidronate treatment for severe Paget's disease is associated with appendicular bone loss. This 2 year study was designed to determine whether cotreatment with calcitriol and a calcium supplement would prevent this. Intravenous pamidronate was used to treat 49 patients with symptomatic Paget's disease. Patients were stratified into two groups of differing biochemical severity based on hydroxyproline excretion (HypE) expressed as micromoles per liter of glomerular filtrate (GF): (1) a severe group with HypE > 10 micromol/L GF; and (2) a moderate group with HypE 5-10 micromol/L GF. Within each group, patients were randomly allocated to receive supplements of calcium and calcitriol (supplemented) or no supplements (unsupplemented) after initiation of pamidronate therapy. The severe group received 360 mg of pamidronate as six doses of 60 mg once weekly and the moderate group received 240 mg as four weekly doses of 60 mg. Patients were followed for 24 months following treatment and had serial bone densitometry of the forearm measured as well as urine and plasma biochemistry. When the groups were combined, the unsupplemented patients showed a decrease in bone mineral density (BMD) at the ultradistal forearm site, which persisted to 24 months. Those supplemented with calcium and calcitriol showed an increase in BMD and the difference between the two groups was significant at all times posttreatment (p < 0.03). When the groups were analyzed separately, those with moderate disease again showed significant differences in BMD between supplemented and unsupplemented patients at all timepoints. In the severe group, the differences did not reach statistical significance due to smaller patient numbers. Similar changes in BMD were also observed at the forearm shaft site. When serial parathyroid hormone (PTH) levels (with the moderate and severe groups combined) were plotted against time since treatment the rise in PTH in the supplemented patients was less than the rise in the unsupplemented patients (p < 0.04). These results suggest that forearm bone loss after intravenous pamidronate treatment for moderate-to-severe Paget's disease can largely be prevented by administration of calcium and calcitriol. The mechanism may be a blunting of the secondary hyperparathyroidism that occurs after intravenous pamidronate. These findings may have wider application in moderate-to-severe Paget's disease treated with other bisphosphonates.

High prevalence of normal total calcium and intact PTH in 60 patients with proven primary hyperparathyroidism: a challenge to current diagnostic criteria.

BACKGROUND: Others have reported a clear distinction between patients with primary hyperparathyroidism (PHPT) and normal subjects using the intact PTH (iPTH) assay. AIM: We reviewed our last 60 surgically proven cases of PHPT, who had adequate preoperative biochemical assessment, to determine the usefulness of the iPTH assay, ionised calcium and other biochemical criteria in differentiating between normal subjects and patients with PHPT. METHODS: We conducted a retrospective cross-sectional study of all patients with surgically proven PHPT who had been referred to Sir Charles Gairdner Hospital, Perth, Western Australia for preoperative biochemical assessment. All cases had fasting preoperative blood and urine samples collected for ionised calcium, plasma total calcium, albumin, urine calcium excretion, renal phosphate threshold and iPTH. RESULTS: Fifty cases had a single or double adenoma and ten had hyperplasia. All except one had ionised hypercalcaemia but only 47 (78%) had an elevated corrected total calcium (cCa). Therefore 13 cases (22%) had a normal cCa and five of those patients (8%) had both an iPTH and cCa within the reference range. Forty-nine (82%) had an elevated ionised calcium (iCa) and iPTH; the remaining 11 (18%) had an iPTH within the reference range. Of this latter 18%, ten (91%) had a low renal phosphate threshold and five (45%) had significant renal calcium conservation: all 11 cases had at least one abnormality in the renal handling of calcium or phosphate and all normalised their plasma calcium postoperatively (ionised and corrected total calcium). CONCLUSIONS: One in five patients with proven PHPT have a non-elevated cCa and/or intact PTH. Ionised calcium should be measured in all suspected cases. Additional studies of renal calcium and phosphate handling are helpful to establish a diagnosis where any uncertainty exists.

Clinical, biochemical, hematologic, and radiographic responses in Paget's disease following intravenous pamidronate disodium: a 2-year study.

An intravenous dosage schedule using pamidronate disodium, based on biochemical severity, was used to treat 71 patients with Paget's disease who had no previous bisphosphonate treatment. Disease severity was stratified by fasting hydroxyproline excretion (HypE): Group (Gp) I (mild disease; HypE < 5.0 mumol/LGF) received a total dose of 120 mg; Gp II (moderate; HypE 5.00-9.99) received 180 mg; and Gp III (severe; HypE > or = 10) received 240 mg. Within each group patients were randomly allocated to receive daily 30 mg or 60 mg infusions. Observations for 2 years included pain scores, indices of bone turnover, and radiology of lytic lesions. There was no difference in biochemical responses, or in the percentage of patients with early fever, between the 30 mg and 60 mg daily subgroups; for convenience, 60 mg infusions are recommended. Neutrophils and total white cell counts were both significantly below baseline 4 days after the first infusion; lymphocytes were significantly reduced by day 2; and all three measures had returned to within the reference range by day 6. Remission was assessed at 6 months, when both plasma alkaline phosphatase (ALP) and HypE had reached stable nadirs. Increasing severity was associated with increasing resistance to suppression of HypE at 6 months to within the reference range: Gp I, 87%; Gp II, 44%; and Gp III, 0% (p < 0.0001 by chi-square test). Biochemical relapse at 2 years (defined as ALP 50% above the 6 month level) was also dependent on initial disease severity (Gp I, 6%; GpII, 39%; Gp III, 62%; p < 0.0005 by chi-square test). There was no association between time to relapse and either initial dose or log dose. Radiologic lytic lesions (in 22 patients) were all in remission at 3 months; however, relapse rates at 2 years appeared to be severity-dependent: Gp I, 13%; Gp II, 43%; and Gp III, 57% (n.s. by chi-square test). Remission rates based on a fall to < 50% of pretreatment of either HypE or ALP were more in accord with lytic lesion remission rates than were rates based on HypE falling to within the reference range. Pamidronate produced a significant reduction from baseline in Pagetic bone, Pagetic joint, and unrelated musculoskeletal pain in the first 6 months (p < 0.0001). From 0 months to 2 years the maintenance of improvement in bone pain (p < 0.005) and joint pain (p < 0.05) was significantly better than in unrelated pain. Pamidronate is a safe, welltolerated, and effective treatment for Paget's disease. In spite of larger dosage in severe disease, increasing severity was associated with resistance to normalization of biochemistry and a higher incidence of biochemical and radiological relapse at 2 years. Our current dosage recommendation would be for two 60 mg infusions for mild disease (Gp I); and four 60 mg infusions for moderate disease (Gp II). Severe disease (Gp III) remains a challenge; regardless of dosage, the majority of patients will be in relapse 2 years after a single course of treatment.

Comparison of biochemical markers of bone turnover in Paget disease treated with pamidronate and a proposed model for the relationships between measurements of the different forms of pyridinoline cross-links.

We have compared the use of new markers of bone turnover in the assessment and treatment of Paget disease and made observations on the mechanisms of bone resorption. Urine hydroxyproline (Hyp) as a bone resorption marker and serum alkaline phosphatase (ALP) as a bone formation marker have traditionally been used to biochemically assess and monitor treatment of Paget disease. Hyp and total ALP were compared with total urine pyridinoline (Pyd) and deoxypyridinoline (Dpd), free urine Pyd and Dpd, urine type I collagen N-terminal cross-linked telopeptide (NTX), type I collagen C-terminal propeptide (PICP), serum osteocalcin, and bone ALP in Paget patients treated with pamidronate. Patients were divided into three biochemical severity-based treatment groups by their fasting urine hydroxyprolline excretion (HypE) levels (Le., group 1, HypE < 5.0 mumol/l of glomerular filtrate [GF]; group 2, HypE of 5.0-9.9 mumol/l of GF; group 3, HypE > 10 mumol/l of GF). Group 1 received one 60 mg intravenous infusion of pamidronate, and groups 2 and 3 received four and six 60 mg infusions at weekly intervals, respectively. Fasting serum and morning urine specimens were taken before and at 2, 6, 13, and 26 weeks after starting treatment. Baseline Z scores were used to compare separation of patient results from normal, and the difference in Z scores from baseline to 13 weeks was used to compare response to treatment. Baseline discrimination and response to treatment at all disease activity levels was greatest for NTX and was poor for osteocalcin, PICP, and C-terminal cross-linked telopeptide of type I collagen (ICTP). The other markers showed good discrimination and response at medium and high levels of disease activity. NTX, total Pyd and Dpd, free Pyd and Dpd, and ICTP are all pyridinoline cross-link-based markers, but discrimination and response by NTX was generally much greater than for the others. Determination of the mechanism of the difference between NTX and other cross-link measures is necessary for appropriate use of the markers and may also lead to a better understanding of the bone resorption process. It has been proposed that the greater sensitivity and discrimination of NTX is because it is more bone-specific than the other cross-link markers with significant amounts of free Pyd and Dpd coming from nonbone sources. We propose another model where the proportion of peptide-bound cross-links such as NTX may be increased in high bone turnover states partly due to a rate-limiting step in their degradation to free cross-links. Conditions with high bone resorption rates would have high levels of NTX that would decline rapidly when resorption rates fall to a level where the capacity to degrade NTX matches the rate of production.

The effects of menopause and age on calcitropic hormones: a cross-sectional study of 655 healthy women aged 35 to 90.

Although women lose 30% of their skeletal mass after the menopause, the mechanism of this loss is uncertain. Clearly estrogen deficiency is important but whether this works only through direct effects on the skeleton is uncertain. To examine these mechanisms further we have evaluated calcium-related metabolic factors in 655 healthy women. Fasting blood samples were collected from all subjects who were up to 35 years past the menopause, and fasting urine and 24-h urine samples were collected in 365 women who were up to 25 years past the menopause. In the first 15 years postmenopause, there was a rise in total plasma calcium due to a rise in albumin. Bone resorption (hydroxyproline creatinine ratio), bone formation (alkaline phosphatase), and the urine calcium creatinine ratio all rose at menopause and remained elevated for the next 25 years. There was a transient further rise in bone resorption for the 10 years following menopause. Neither PTH nor the free calcitriol index changed for the first 10 years following menopause. Ten years past the menopause, although total calcitriol rose, the free calcitriol index fell due to a rise in vitamin D binding protein. PTH began to rise at 15 years past menopause. GFR fell gradually over the 25 years following menopause. Thus following menopause there is an increase in bone turnover and increased urine calcium loss independent of any effect of PTH or calcitriol, suggesting a direct effect of estrogen deficiency on bone and kidney.(ABSTRACT TRUNCATED AT 250 WORDS)