Intra-operative parathyroid hormone evaluation is superior to frozen section analysis in parathyroid surgery.

BACKGROUND: Surgery is currently the only treatment option for patients with primary hyperparathyroidism (PHPT). Recently, minimally invasive parathyroidectomy (MIP) has begun to replace traditional bilateral neck exploration (BNE). OBJECTIVE: The aim of this study is to compare the results of parathyroidectomies performed in our hospital over the past decade that were guided by intra-operative parathyroid hormone (IOPTH) sampling or frozen section (FS) analysis. MATERIAL AND METHODS: Data on 697 patients who underwent parathyroidectomies in the Department of Endocrine Surgery, Dokuz Eylul University between January 2005 and 2018 were included in this study. Patients with malignancies other than thyroid papillary microcarcinoma and parathyroid cancer were excluded from the study. RESULTS: The concomitant use of neck ultrasound (US) and technetium 99m Sestamibi (99mTc MIBI) scintigraphy successfully localized the hyperfunctioning parathyroid glands in nearly 96% of cases. As compared with the IOPTH group, the operation time was longer in the FS group (p < 0.001), and the need for postoperative calcium (Ca) supplementation was higher (p < 0.001). The duration of hospitalization (days) was significantly higher in the FS group (4.2 ± 3.4 vs. 2.6 ± 1.9) as compared with that in the IOPTH group (p < 0.001). In addition, the recurrence rate in the FS group was significantly higher than that in the IPOTH group (p = 0.002). CONCLUSION: IOPTH sampling is a safe and effective method when performed by experienced surgeons and with appropriate preoperative screening. This study emphasizes that IOPTH sampling. We believe that the success in parathyroid surgery is due to three factors: correct indication, accurate localization and experienced surgeon.

Physical Activity-Dependent Regulation of Parathyroid Hormone and Calcium-Phosphorous Metabolism.

Exercise perturbs homeostasis, alters the levels of circulating mediators and hormones, and increases the demand by skeletal muscles and other vital organs for energy substrates. Exercise also affects bone and mineral metabolism, particularly calcium and phosphate, both of which are essential for muscle contraction, neuromuscular signaling, biosynthesis of adenosine triphosphate (ATP), and other energy substrates. Parathyroid hormone (PTH) is involved in the regulation of calcium and phosphate homeostasis. Understanding the effects of exercise on PTH secretion is fundamental for appreciating how the body adapts to exercise. Altered PTH metabolism underlies hyperparathyroidism and hypoparathyroidism, the complications of which affect the organs involved in calcium and phosphorous metabolism (bone and kidney) and other body systems as well. Exercise affects PTH expression and secretion by altering the circulating levels of calcium and phosphate. In turn, PTH responds directly to exercise and exercise-induced myokines. Here, we review the main concepts of the regulation of PTH expression and secretion under physiological conditions, in acute and chronic exercise, and in relation to PTH-related disorders.

Salivary levels of calcium, phosphorus, potassium, albumin and correlation with serum biomarkers in hemodialysis patients.

OBJECTIVES: Evidences suggest that hemodialysis patients have reduced salivary flow and changes in the composition of salivary secretion. These changes may reflect local and systemic disorders. The objectives of this study were to compare the salivary levels of calcium (Ca), phosphorus (P), potassium (K) and albumin in hemodialysis patients and healthy subjects, and to investigate a possible correlation between their serum and salivary levels. DESIGN: A case-control study was conducted with 60 hemodialysis patients (HD group) and 37 systemically healthy individuals (control group). Stimulated saliva samples were collected for biochemical analysis (Ca, P, K and albumin). Serum data were collected in the HD group. Statistical analysis included t-test, Pearson correlation and simple linear regression. RESULTS: The HD group exhibited higher salivary levels of Ca, P, and albumin (p<0.05). There was a significant positive correlation between serum PTH and salivary phosphorus (r=0.342, p=0.009), and between serum PTH and salivary potassium (r=0.306, p=0.020). An increase of 100 pg/dL in serum PTH was associated with an elevation of salivary P levels (0.34 mg/dL, p=0.009), and salivary K levels (0.20 mmol/dL, p=0.02), in the HD group. CONCLUSIONS: The findings suggest that HD patients present increased levels of salivary components (Ca, P, and albumin), and changes commonly observed in HD patients, such as hyperparathyroidism, appear to have an influence on salivary composition.

[Hormonal and metabolic disorders as systemic factor for the formation of urinary calculi].

In patients suffering from urolithiasis, metabolic diagnostics often reveals abnormalities contributing to the formation of stones: hypocitraturia, hyper- and hypocalcemia, hypercalciuria, hypomagnesemia/hypomagnesuria, hyperoxalaturia, etc. Before surgery, complex biochemical examination of blood and 24-hourcollection urine in 82 patients with urolithiasis was performed. The analysis of the main laboratory parameters of carbohydrate, lipid, calcium and phosphorus and purine metabolism found the prevalence of violations of calcium and phosphorus metabolism in these patients. Dyslipidemia was diagnosed in 31 (37.8%) patients. There was a significant positive correlation between serum total cholesterol and serum total calcium (rs = 0.3315, P = 0.0103). Low serum calcium levels were associated with hyperoxalaturia (rs = -0.4270, P = 0.0295). There was a significant effect of natriuria on urinary excretion of oxalate (rs = 0.6107, P = 0.0001), Mg (rs = 0.4156, P = 0.0096) and K (rs = 0.5234, P = 0.00005). The study shows the role of magnesium in the prevention of recurrence and manifestation of urolithiasis. The combination of two or more types of hormonal and metabolic disorders increases the incidence of recurrent stones. Timely correction of hormonal-metabolic status allows to reduce the risk of stone formation, and hospitalization attributable to the complications associated.

Mono- and polyphosphates have similar effects on calcium and phosphorus metabolism in healthy young women.

PURPOSE: Phosphate (Pi) salts, often mono- (MP) or polyphosphates (PP), are commonly used as additives in the food industry. Previous studies have shown that the effects of MP and PP on calcium (Ca) and phosphorus (P) metabolism may differ. The aim of this study was to determine whether the effects of MP and PP salts differ on markers of Ca and P metabolism in young women. METHODS: Fourteen healthy women 19-31 years of age were randomized into three controlled 24-h study sessions, each subject serving as her own control. During each session, the subjects received three doses of MP, PP or a placebo with meals in randomized order. Both Pi salts provided 1,500 mg P/d, and the diet during each session was identical. Markers of Ca and P metabolism were followed six times over 24 h. RESULTS: During both MP and PP sessions, we found an increase in serum phosphate (S-Pi, p = 0.0001), urinary phosphate (U-Pi, p = 0.0001) and serum parathyroid hormone (S-PTH, p = 0.048 MP, p = 0.012 PP) relative to the control session. PP decreased U-Ca more than did MP (p = 0.014). CONCLUSIONS: The results suggest that PP binds Ca in the intestine more than does MP. Based on the S-Pi, U-Pi and S-PTH results, both Pi salts are absorbed with equal efficiency. In the long run, increased S-PTH, caused by either an MP or PP salt, could have negative effects on bone metabolism.

The abnormal phenotypes of cartilage and bone in calcium-sensing receptor deficient mice are dependent on the actions of calcium, phosphorus, and PTH.

Patients with neonatal severe hyperparathyroidism (NSHPT) are homozygous for the calcium-sensing receptor (CaR) mutation and have very high circulating PTH, abundant parathyroid hyperplasia, and severe life-threatening hypercalcemia. Mice with homozygous deletion of CaR mimic the syndrome of NSHPT. To determine effects of CaR deficiency on skeletal development and interactions between CaR and 1,25(OH)(2)D(3) or PTH on calcium and skeletal homeostasis, we compared the skeletal phenotypes of homozygous CaR-deficient (CaR(-/-)) mice to those of double homozygous CaR- and 1α(OH)ase-deficient [CaR(-/-)1α(OH)ase(-/-)] mice or those of double homozygous CaR- and PTH-deficient [CaR(-/-)PTH(-/-)] mice at 2 weeks of age. Compared to wild-type littermates, CaR(-/-) mice had hypercalcemia, hypophosphatemia, hyperparathyroidism, and severe skeletal growth retardation. Chondrocyte proliferation and PTHrP expression in growth plates were reduced significantly, whereas trabecular volume, osteoblast number, osteocalcin-positive areas, expression of the ALP, type I collagen, osteocalcin genes, and serum ALP levels were increased significantly. Deletion of 1α(OH)ase in CaR(-/-) mice resulted in a longer lifespan, normocalcemia, lower serum phosphorus, greater elevation in PTH, slight improvement in skeletal growth with increased chondrocyte proliferation and PTHrP expression, and further increases in indices of osteoblastic bone formation. Deletion of PTH in CaR(-/-) mice resulted in rescue of early lethality, normocalcemia, increased serum phosphorus, undetectable serum PTH, normalization in skeletal growth with normal chondrocyte proliferation and enhanced PTHrP expression, and dramatic decreases in indices of osteoblastic bone formation. Our results indicate that reductions in hypercalcemia play a critical role in preventing the early lethality of CaR(-/-) mice and that defects in endochondral bone formation in CaR(-/-) mice result from effects of the marked elevation in serum calcium concentration and the decreases in serum phosphorus concentration and skeletal PTHrP levels, whereas the increased osteoblastic bone formation results from direct effects of PTH.

The effect of cinacalcet on bone remodeling and renal function in transplant patients with persistent hyperparathyroidism.

BACKGROUND: Parathyroidectomy is associated with renal functional losses in transplant patients; cinacalcet offers an attractive alternative. METHODS: We performed a prospective observational study in 58 patients with persisting hyperparathyroidism after renal transplantation (Ca≥2.6 mmol/L) and impaired renal transplant function (estimated glomerular filtration rate [eGFR] <50 mL/min). The patients received 30 to 90 mg cinacalcet for 12 months with the target to normalize serum Ca. We measured parathyroid hormone (PTH), serum Ca, serum phosphorus, alkaline phosphatase, bone-specific alkaline phosphatase, osteocalcin, and telopeptide at 0, 1, 2, 3, 6, 9, and 12 months of cinacalcet treatment. Fractional excretion of calcium and phosphorus (n=24) were monitored at 0 and 1 month. RESULTS: At inclusion, creatinine was 181±70 µmol/L, eGFR 43±19 mL/min, PTH 371±279 pg/mL, and Ca 2.73±0.22 mmol/L. We observed nephrocalcinosis in 58% of biopsied patients at enrollment. After cinacalcet, Ca decreased significantly and normalized at nearly any measurement. Phosphorus increased significantly at months 1, 9, and 12. PTH decreased significantly, but only at months 9 and 12 and did not normalize. Bone-specific alkaline phosphatase increased significantly (>normal) by month 12. eGFR decreased and serum creatinine increased at all time points. The Δ(creatinine) % increase correlated significantly with the Δ(PTH) % decrease at month 1 and 12. Telopeptide and alkaline phosphatase correlated with PTH and telopeptide also correlated with serum creatinine. CONCLUSION: Calcium-phosphorus homeostasis in hypercalcemic renal transplant patients normalizes under cinacalcet and PTH decreases, albeit not to normal. The renal functional decline could be PTH mediated, analogous to the effects observed after parathyroidectomy.

Effect of paricalcitol and cinacalcet on serum phosphate, FGF-23, and bone in rats with chronic kidney disease.

Calcimimetics activate the calcium-sensing receptor (CaR) and reduce parathyroid hormone (PTH) by increasing the sensitivity of the parathyroid CaR to ambient calcium. The calcimimetic, cinacalcet, is effective in treating secondary hyperparathyroidism in dialysis patients [chronic kidney disease (CKD 5)], but little is known about its effects on stage 3-4 CKD patients. We compared cinacalcet and paricalcitol in uremic rats with creatinine clearances "equivalent" to patients with CKD 3-4. Uremia was induced in anesthetized rats using the 5/6th nephrectomy model. Groups were 1) uremic control, 2) uremic + cinacalcet (U+Cin; 15 mg x kg(-1) x day(-1) po for 6 wk), 3) uremic + paricalcitol (U+Par; 0.16 microg/kg, 3 x wk, ip for 6 wk), and 4) normal. Unlike U+Par animals, cinacalcet promoted hypocalcemia and marked hyperphosphatemia. The Ca x P in U+Cin rats was twice that of U+Par rats. Both compounds suppressed PTH. Serum 1,25-(OH)(2)D(3) was decreased in both U+Par and U+Cin rats. Serum FGF-23 was increased in U+Par but not in U+Cin, where it tended to decrease. Analysis of tibiae showed that U+Cin, but not U+Par, rats had reduced bone volume. U+Cin rats had similar bone formation and reduced osteoid surface, but higher bone resorption. Hypocalcemia, hyperphosphatemia, low 1,25-(OH)(2)D(3), and cinacalcet itself may play a role in the detrimental effects on bone seen in U+Cin rats. This requires further investigation. In conclusion, due to its effects on bone and to the hypocalcemia and severe hyperphosphatemia it induces, we believe that cinacalcet should not be used in patients with CKD without further detailed studies.

Presence of a deletion mutation (c.716delA) in the ligand binding domain of the vitamin D receptor in an Indian patient with vitamin D-dependent rickets type II.

Vitamin D-dependent rickets type II (VDDR-type II) is a rare disorder caused by mutations in the vitamin D receptor (VDR) gene. Here, we describe a patient with VDDR-type II with severe alopecia and rickets. She had hypocalcemia, hypophosphatemia, secondary hyperparathyroidism, and elevated serum alkaline phosphatase and 1,25-dihydroxyvitamin D(3). Sequence analysis of the lymphocyte VDR cDNA revealed deletion mutation c.716delA. Sequence analysis of her genomic DNA fragment amplified from exon 6 of the VDR gene incorporating this mutation confirmed the presence of the mutation in homozygous form. This frameshift mutation in the ligand binding domain (LBD) resulted in premature termination (p.Lys240Argfs) of the VDR protein. The mutant protein contained 246 amino acids, with 239 normal amino acids at the N terminus, followed by seven changed amino acids resulting in complete loss of its LBD. The mutant VDR protein showed evidence of 50% reduced binding with VDR response elements on electrophoretic mobility assay in comparison to the wild-type VDR protein. She was treated with high-dose calcium infusion and oral phosphate. After 18 months of treatment, she gained 6 cm of height, serum calcium and phosphorus improved, alkaline phosphatase levels decreased, and intact PTH normalized. Radiologically, there were signs of healing of rickets. Her parents and one of her siblings had the same c.716delA mutation in heterozygous form. Despite the complete absence of LBD, the rickets showed signs of healing with intravenous calcium.

Calcimimetic inhibits late-stage cyst growth in ADPKD.

In polycystic kidney disease (PKD), genetic mutations in polycystin 1 and 2 lead to defective intracellular trafficking of calcium, thereby decreasing intracellular calcium and altering cAMP signaling to favor proliferation. We hypothesized that calcimimetics, allosteric modulators of the calcium-sensing receptor, would reduce cyst growth by increasing intracellular calcium. We randomly assigned 20-wk-old male rats with a form of autosomal dominant PKD (heterozygote Cy/+) to one of four groups for 14 to 18 wk of treatment: (group 1) no treatment; (group 2) calcimimetic R-568 formulated in the diet; (group 3) R-568 plus calcium-supplemented drinking water (R-568 plus Ca); or (group 4) Ca-supplemented drinking water with a normal diet (Ca). Severity of PKD did not progress in any of the three treatment groups between 34 and 38 wk. Compared with no treatment, cyst growth was unaffected at 34 wk by all treatments, but cyst volume and fibrosis were lower at 38 wk, with both R-568-treated groups demonstrating a greater reduction than calcium alone. Between 34 and 38 wk, the total kidney weight increased by 78% in the control group (P < 0.001) and by 19% in the Ca group (P < 0.01), but did not increase in the R-568 or R-568 plus Ca groups, suggesting inhibition of disease progression despite equivalent suppression of parathyroid hormone. In summary, treatment of hyperparathyroidism halts late-stage progression of rodent cystic kidney disease. The benefit of R-568 alone suggests calcium-sensing receptor modulation may have additional inhibitory effects on late-stage cyst growth resulting from a direct modulation of intracellular calcium.

Diaminobutane (DAB) dendrimers are potent binders of oral phosphate.

Reduction of blood phosphorus is a critical component in the management of secondary hyperparathyroidism in chronic kidney disease patients. In addition to dialysis treatment and dietary phosphorus restriction, oral phosphate binders are often consumed with meals to reduce the availability of food phosphorus. Several oral phosphate binders are approved for use in chronic kidney disease patients, but all have practical limitations because of toxicity, poor efficacy, or high cost. Using an in vivo method to measure intestinal phosphate absorption in rats using radiolabeled phosphate, we found that first-, second-, third-, and fifth-generation diaminobutane dendrimer compounds, DAB-4-Cl, DAB-8-Cl, DAB-16-Cl, and DAB-64-Cl, respectively, drastically reduce the absorption of inorganic phosphate in a dose-dependent manner. To avoid complications of metabolic acidosis caused by hydrochloride salts, an acetate salt, DAB-9-AcOH, was prepared and shown to be equally effective at binding radiolabeled phosphate as DAB-8-Cl. DAB-8-AcOH was further shown to increase fecal phosphorus and decrease serum phosphorus in a dose-dependent manner when fed to rats. These data suggest that dendrimer compounds are of great potential use in the binding of food phosphate for the management of hyperparathyroidism secondary to chronic kidney disease.

Treatment of secondary hyperparathyroidism in CKD patients with cinacalcet and/or vitamin D derivatives.

The discovery of the calcium-sensing receptor (CaR) 15 yr ago was rapidly followed by the development of drugs modulating its activity, the so-called calcimimetics (increasing the CaR signal) and calcilytics (decreasing the CaR signal). The indication for calcimimetics is treatment of primary and secondary hyperparathyroidism, whereas calcilytics have potential for treatment of osteoporosis. A large number of clinical studies has shown that cinacalcet, the only presently available calcimimetic, effectively reduces serum parathyroid hormone in dialysis patients with secondary hyperparathyroidism. In contrast to the effect of active vitamin D derivatives, it simultaneously decreases serum calcium and phosphorus. Experimental studies showed a concomitant decrease in parathyroid hyperplasia. In the treatment of secondary hyperparathyroidism of dialysis patients, important questions remain unresolved, for example, whether there are reasons to prefer calcimimetics to active vitamin D derivatives and whether combined administration offers advantages compared with calcimimetics or active vitamin D given in isolation. For lowering parathyroid hormone, available evidence from recent studies suggests that combination therapy should be preferred to single drug treatment because of less side-effects and greater efficacy in controlling parathyroid overfunction. Future randomized controlled trial must answer whether calcimimetics impact on cardiovascular events or survival and whether in this respect there are differences between vitamin D sterols and calcimimetics.

Accelerated bone resorption, due to dietary calcium deficiency, promotes breast cancer tumor growth in bone.

The skeleton is a major site of breast cancer metastases. High bone turnover increases risk of disease progression and death. However, there is no direct evidence that high bone turnover is causally associated with the establishment and progression of metastases. In this study, we investigate the effects of high bone turnover in a model of breast cancer growth in bone. Female nude mice commenced a diet containing normal (0.6%; 'Normal-Ca') or low (0.1%; 'Low-Ca') calcium content. Mice were concurrently treated with vehicle or osteoprotegerin (1 mg/kg/d s.c; n = 16 per group). Three days later (day 0), 50,000 Tx-SA cells (variant of MDA-MB-231 cells) were implanted by intratibial injection. On day 0, mice receiving Low-Ca had increased serum parathyroid hormone (PTH) and tartrate-resistant acid phosphatase 5b levels, indicating secondary hyperparathyroidism and high bone turnover, which was maintained until day 17. Osteoprotegerin increased serum PTH but profoundly reduced bone resorption. On day 17, in mice receiving Low-Ca alone, lytic lesion area, tumor area, and cancer cell proliferation increased by 43%, 24%, and 24%, respectively, compared with mice receiving Normal Ca (P < 0.01). Osteoprotegerin treatment completely inhibited lytic lesions, reduced tumor area, decreased cancer cell proliferation, and increased cancer cell apoptosis. Increased bone turnover, due to dietary calcium deficiency, promotes tumor growth in bone, independent of the action of PTH. Breast cancer patients frequently have low dietary calcium intake and high bone turnover. Treatment to correct calcium insufficiency and/or treatment with antiresorptive agents, such as osteoprotegerin, may be of benefit in the adjuvant as well as palliative setting.

Vitamin D levels and early mortality among incident hemodialysis patients.

Vitamin D deficiency is associated with cardiovascular disease, the most common cause of mortality in hemodialysis patients. To investigate the relation between blood levels of 25-hydroxyvitamin D (25D) and 1,25-dihydroxyvitamin D (1,25D) with hemodialysis outcomes, we measured baseline vitamin D levels in a cross-sectional analysis of 825 consecutive patients from within a prospective cohort of incident US hemodialysis patients. Of these patients, 78% were considered vitamin D deficient with 18% considered severely deficient. Calcium, phosphorus, and parathyroid hormone levels correlated poorly with 25D and 1,25D concentrations. To test the association between baseline vitamin D levels and 90-day mortality, we selected the next 175 consecutive participants who died within 90 days and compared them to the 750 patients who survived in a nested case-control analysis. While low vitamin D levels were associated with increased mortality, significant interaction was noted between vitamin D levels, subsequent active vitamin D therapy, and survival. Compared to patients with the highest 25D or 1,25D levels who received therapy, untreated deficient patients were at significantly increased risk for early mortality. Our study shows that among incident hemodialysis patients, vitamin D deficiency is common, correlates poorly with other components of mineral metabolism and is associated with increased early mortality.

Identification and functional characterization of a novel mutation in the calcium-sensing receptor gene in familial hypocalciuric hypercalcemia: modulation of clinical severity by vitamin D status.

CONTEXT: Familial hypocalciuric hypercalcemia (FHH) is a benign condition associated with heterogeneous inactivating mutations in the calcium-sensing receptor (CASR) gene. OBJECTIVE: The objective of the study was to identify and characterize a CASR mutation in a moderately hypercalcemic, hyperparathyroid individual and his family and assess the influence of vitamin D status on the clinical expression of the defect. SUBJECTS: We studied a kindred with FHH, in which the proband (a 34-yr-old male) was initially diagnosed with primary hyperparathyroidism due to frankly elevated serum PTH levels. METHODS: CASR gene mutation analysis was performed on genomic DNA of the proband and family members. The mutant CASR was functionally characterized by transient transfection studies in kidney cells in vitro. RESULTS: A novel heterozygous mutation (F180C, TTC>TGC) in exon 4 of the CASR gene was identified. Although the mutant receptor was expressed normally at the cell surface, it was unresponsive with respect to intracellular signaling (MAPK activation) to increases in extracellular calcium concentrations. The baby daughter of the proband presented with neonatal hyperparathyroidism with markedly elevated PTH. Vitamin D supplementation of both the proband and the baby resulted in reduction of serum PTH levels to the normal range. The serum calcium level remained at a constant and moderately elevated level. CONCLUSION: The identification of a novel CASR gene mutation established the basis of the hypercalcemia in the kindred. Concomitant vitamin D deficiency modulates the severity of the presentation of FHH.

Relation between Tc-99m sestamibi uptake and biological factors in hyperparathyroidism.

PURPOSE: The aim of this study was to evaluate the relation between uptake ratios of Tc-99m sestamibi (MIBI) and tumor volume, serum biochemical values (i-PTH, Ca, P) and oxyphil cell content. MATERIALS AND METHODS: The study population consisted of 19 patients (2 M, 17 F; mean +/- SD: 47 +/- 12 y). Anterior planar images of the neck and chest were acquired early (15 min) and triple late phase (1, 2 and 3-4 h) after intravenous injections of 740 MBq MIBI. Each of the surgical materials was reviewed retrospectively. The percentage of cell type (chief, oxyphil and clear cells) in the tumors was calculated by light microscopy. RESULTS: The uptake ratio obtained from L1 (1 hour) phase was found to be higher than the uptake ratio obtained from early phase, and the difference was statistically significant (1.57 +/- 0.34 and 1.43 +/- 0.29, p = 0.004, respectively). There was no significant correlation between uptake ratios that were obtained from 4 different imaging phases and lesion volumes, i-PTH levels and calcium levels (p > 0.05). However, there was a significant adverse correlation between L2 and L3 uptake ratios and serum phosphorus values (r = -0.44, p = 0.04 and r = -0.46, p = 0.04, respectively). Additionally, no significant correlation between MIBI uptake ratios of each imaging phase and the laboratory data, volume of lesion or oxyphil percentage volume was found after the multiple regression analysis (E: p = 0.46, r = 0.49; L1: p = 0.24, r = 0.58; L2: p = 0.27, r = 0.57; L3: p = 0.32, r = 0.55, respectively. There was no correlation between gland oxyphil percentage volume and MIBI uptake ratios (p > 0.05). CONCLUSION: The results of our study show that the optimal imaging times after intravenous injection of MIBI are 15 minutes and 1 hour because of the shorter examination time without loss of diagnostic ability. In the present study, there was no significant correlation between MIBI uptake ratios and increased gland volume, or serum Ca and i-PTH levels. Besides, we think that oxyphil cell content may not have a main effect on MIBI uptake and retention. The fact of an adverse relation between phosphorus and MIBI retention in our study suggests that phosphorus level should be considered prior to MIBI imaging.

[Disorders of calcium metabolism during pregnancy and breast feeding]. / Zaburzenia gospodarki wapniowo-fosforanowej w ciazy i podczas laktacji.

Hypoparathyroidism following thyroidectomy or due to autoimmune process is the most common cause of hypocalcaemia. If untreated, maternal hypocalcaemia may stimulate fetal parathyroids which results in bone demineralization. Calcium supplementation may also reduce the risk of hypertension. Moreover, hypocalcaemia may inhibit the synthesis of calcium gene-related peptide (CGRP), which, in turn, decreases blood pressure and uterus contractions. In women of reproductive age hypercalcaemia is mostly due to hyperparathyroidism. The complications include toxemia, vomiting, and hypercalcaemic crisis. Maternal hypercalcaemia can suppress fetal parathyroid function and cause neonatal hypocalcaemia. The pharmacotherapy involves diuretics, fluids and oral phosphates. Bisphosphonates are contraindicated. Parathyroid surgery may be performed in the second trimester of pregnancy.

Metabolic assessment in patients with urinary lithiasis.

INTRODUCTION: Metabolic investigation in patients with urinary lithiasis is very important for preventing recurrence of disease. The objective of this work was to diagnose and to determine the prevalence of metabolic disorders, to assess the quality of the water consumed and volume of diuresis as potential risk factors for this pathology. PATIENTS AND METHODS: We studied 182 patients older than 12 years. We included patients with history and/or imaging tests confirming at least 2 stones, with creatinine clearance > or = 60 mL/min and negative urine culture. The protocol consisted in the collection of 2, 24-hour urine samples, for dosing Ca, P, uric acid, Na, K, Mg, Ox and Ci, glycemia and serum levels of Ca, P, Uric acid, Na, K, Cl, Mg, U and Cr, urinary pH and urinary acidification test. RESULTS: 158 patients fulfilled the inclusion criteria. Among these, 151 (95.5%) presented metabolic changes, with 94 (62.2%) presenting isolated metabolic change and 57 (37.8%) had mixed changes. The main disorders detected were hypercalciuria (74%), hypocitraturia (37.3%), hyperoxaluria (24.1%), hypomagnesuria (21%), hyperuricosuria (20.2%), primary hyperparathyroidism (1.8%), secondary hyperparathyroidism (0.6%) and renal tubular acidosis (0.6). CONCLUSION: Metabolic change was diagnosed in 95.5% of patients. These results warrant the metabolic study and follow-up in patients with recurrent lithiasis in order to decrease the recurrence rate through specific treatments, modification in alimentary and behavioral habits.

Metabolic assessment in patients with urinary lithiasis

INTRODUCTION: Metabolic investigation in patients with urinary lithiasis is very important for preventing recurrence of disease. The objective of this work was to diagnose and to determine the prevalence of metabolic disorders, to assess the quality of the water consumed and volume of diuresis as potential risk factors for this pathology. PATIENTS AND METHODS: We studied 182 patients older than 12 years. We included patients with history and/or imaging tests confirming at least 2 stones, with creatinine clearance > 60 mL/min and negative urine culture. The protocol consisted in the collection of 2, 24-hour urine samples, for dosing Ca, P, uric acid, Na, K, Mg, Ox and Ci, glycemia and serum levels of Ca, P, Uric acid, Na, K, Cl, Mg, U and Cr, urinary pH and urinary acidification test. RESULTS: 158 patients fulfilled the inclusion criteria. Among these, 151 (95.5 percent) presented metabolic changes, with 94 (62.2 percent) presenting isolated metabolic change and 57 (37.8 percent) had mixed changes. The main disorders detected were hypercalciuria (74 percent), hypocitraturia (37.3 percent), hyperoxaluria (24.1 percent), hypomagnesuria (21 percent), hyperuricosuria (20.2 percent), primary hyperparathyroidism (1.8 percent) secondary hyperparathyroidism (0.6 percent) and renal tubular acidosis (0.6). CONCLUSION: Metabolic change was diagnosed in 95.5 percent of patients. These results warrant the metabolic study and follow-up in patients with recurrent lithiasis in order to decrease the recurrence rate through specific treatments, modification in alimentary and behavioral habits.

The impact of calcimimetic agents on the use of different classes of phosphate binders: results of recent clinical trials.

Calcimimetic agents bind to and activate the calcium-sensing receptor in the parathyroid glands, lowering the threshold for its activation by extracellular calcium and diminishing parathyroid hormone release from parathyroid cells. In three large randomized, controlled trials, cinacalcet given at doses of 30 to 180 mg orally each day was associated with effective reduction in parathyroid hormone levels over 26 weeks compared with placebo, and was consistently associated with a decrement in serum calcium, phosphorus levels, as well as a decrement in calcium-phosphorus product. In one study, there was a 5% incidence of hypocalcemia (serum calcium levels < 7.5 mg/dL on at least two consecutive measurements) among patients receiving cinacalcet, and less than 1% of patients receiving standard therapy (P < 0.0001). While there were no demonstrated differences between groups with regard to use of phosphate binders and vitamin D sterols in these randomized controlled trials, arguably, the combination of the effects on serum calcium, phosphorus, and calcium-phosphorus product may bring increased focus on the increased mortality risk associated with hypocalcemia.