Treatment of hypocalcemia caused by hypoparathyroidism or pseudohypoparathyroidism with domestic-made calcitriol: a prospective and self-controlled clinical trial.

BACKGROUND: Parathyroid hormone deficiency or resistance may cause hypocalcemia with related symptoms and signs. Lifelong treatment of calcium combined with vitamin D or its metabolites is always necessary for these patients. Here we reported a prospective and open-label trial to investigate the efficacy and safety of domestic-made calcitriol in treatment of hypocalcemia caused by hypoparathyroidism or pseudohypoparathyroidism. METHODS: Twenty-four patients with confirmed hypoparathyroidism or pseudohypoparathyroidism aged (36.5 +/- 11.0) years old were studied. Among them, 16 patients had idiopathic hypoparathyroidism, 2 had pseudohypoparathyroidism and 6 had hypoparathyroidism secondary to cervical surgery. Serum calcium levels were lower than 1.88 mmol/L. Oral calcitriol was administered twice or three times with elemental calcium 1.2 g per day. All patients were followed every 4 weeks throughout the 12-week period. Dose adjustments of calcitriol were based on serum and urinary calcium levels and symptoms of hypocalcemia. RESULTS: Twenty patients were included by the end of this study. Muscular weakness, cramps, extremity paresthesia, Chovestek's sign and Trousseau's sign were relieved in 76.9%, 100%, 94.4%, 93.3% and 78.9% of patients, respectively. Serum calcium, plasma ionized calcium and serum phosphorus levels were (1.54+/-0.25) mmol/L, (0.64+/-0.10) mmol/L and (2.00+/-0.46) mmol/L at baseline, and reached (2.20+/-0.20) mmol/L, (0.95+/-0.06) mmol/L and (1.68+/-0.25) mmol/L (P<0.01) at the 12th week of treatment, respectively. Eighty percent of patients were assessed as effective and 20% as partly effective. Three, four and eight patients had hypercalciuria at the 4th, 8th and 12th week of treatment, respectively, which were reduced by thiazide diuretics. The final dose of calcitriol was (1.09+/-0.50) microg/d. CONCLUSIONS: Calcitriol combined with calcium can be used in treatment of hypocalcemia caused by hypoparathyroidism or pseudohypoparathyroidism effectively and safely. Serum and urinary calcium levels should be monitored during the course of the therapy.

PTH(1-34) replacement therapy in a child with hypoparathyroidism caused by a sporadic calcium receptor mutation.

Autosomal dominant hypocalcemia (ADH) is an inherited form of hypoparathyroidism caused by activating mutations in the calcium-sensing receptor (CaR). Treatment with PTH(1-34) may be superior to conventional therapy but is contraindicated in children, and long-term effects on the skeleton are unknown. The patient is a 20-yr-old female with ADH treated with PTH continuously since 6 yr and 2 mo of age. A bone biopsy was obtained for histomorphometry and quantitative backscattered electron imaging (qBEI). Her data were compared with one age-, sex-, and length of hypoparathyroidism-matched control not on PTH and two sex-matched ADH controls before and after 1 yr of PTH. The patient's growth was normal. Hypercalciuria and hypermagnesuria persisted despite normal or subnormal serum calcium and magnesium levels. Nephrocalcinosis, without evidence of impaired renal function, developed by 19 yr of age. Cancellous bone volume was dramatically elevated in the patient and in ADH controls after 1 yr of PTH. BMD distribution (BMDD) by qBEI of the patient and ADH controls was strikingly shifted toward lower mineralization compared with the non-ADH control. Moreover, the ADH controls exhibited a further reduction in mineralization after 1 yr of PTH. These findings imply a role for CaR in bone matrix mineralization. There were no fractures or osteosarcoma. In conclusion, long-term PTH replacement in a child with ADH was not unsafe, increased bone mass without negatively impacting mineralization, and improved serum mineral control but did not prevent nephrocalcinosis. Additionally, this may be the first evidence of a role for CaR in human bone.

Effects of once versus twice-daily parathyroid hormone 1-34 therapy in children with hypoparathyroidism.

CONTEXT: Hypoparathyroidism is among the few hormonal insufficiency states not treated with replacement of the missing hormone. Long-term conventional therapy with vitamin D and analogs may lead to nephrocalcinosis and renal insufficiency. OBJECTIVE: Our objective was to compare the response of once-daily vs. twice-daily PTH 1-34 treatment in children with hypoparathyroidism. SETTING: The study was conducted at a clinical research center. SUBJECTS: Fourteen children ages 4-17 yr with chronic hypoparathyroidism were studied. STUDY DESIGN: This was a randomized cross-over trial, lasting 28 wk, which compared two dose regimens, once-daily vs. twice-daily PTH1-34. Each 14-wk study arm was divided into a 2-wk inpatient dose-adjustment phase and a 12-wk outpatient phase. RESULTS: Mean predose serum calcium was maintained at levels just below the normal range. Repeated serum measures over a 24-h period showed that twice-daily PTH 1-34 increased serum calcium and magnesium levels more effectively than a once-daily dose. This was especially evident during the second half of the day (12-24 h). PTH 1-34 normalized mean 24-h urine calcium excretion on both treatment schedules. This was achieved with half the PTH 1-34 dose during the twice-daily regimen compared with the once-daily regimen (twice-daily, 25 +/-15 microg/d vs. once-daily, 58 +/- 28 microg/d; P < 0.001). CONCLUSIONS: We conclude that a twice-daily PTH 1-34 regimen provides a more effective treatment of hypoparathyroidism compared with once-daily treatment because it reduces the variation in serum calcium levels and accomplishes this at a lower total daily PTH 1-34 dose. The results showed, as in the previous study of adult patients with hypoparathyroidism, that a twice-daily regimen produced significantly improved metabolic control compared with once-daily PTH 1-34.

Effect of parathyroid hormone administration in a patient with severe hypoparathyroidism caused by gain-of-function mutation of calcium-sensing receptor.

Hypoparathyroidism caused by gain-of-function mutations of the calcium-sensing receptor (CaR) in the transmembrane domain is usually severe and difficult to manage. A patient with severe hypoparathyroidism, caused by CaR activating mutation F821L, was treated for 3 days (Day 1 to Day 3) with synthetic human parathyroid hormone 1-34 (teriparatide, PTH). An Ellsworth-Howard test of the patient revealed normal responses of urine phosphate and cyclic AMP excretion, indicating that the patient's renal tubules normally responded to extrinsic PTH. On Day 1 to Day 3, 0.9 microg/kg/day of PTH was administered subcutaneously twice daily at 0800 and 2000. On Day 1, the serum calcium level that was 1.8 mmol/l before PTH administration increased to 2.1 mmol/l at 1200, and gradually decreased to 1.8 mmol/l at 2000. On Days 2 and 3, the maximum calcium levels were 2.5 and 2.4 mmol/l, respectively, at 1200. At 2000, they returned to or below basal levels at 0800. On Day 4 without PTH administration, the calcium levels were maintained at the basal levels at Day 0. The urine calcium/creatinine (Ca/Cr) ratio that was high (>0.4) before PTH injection decreased after PTH administration (0.4>). Changes in the ionized calcium levels were almost parallel with the total calcium levels. The serum inorganic phosphate (IP) level decreased to 2.4 mmol/l at 1000, but gradually increased before the second PTH injection to the level at 0800 on Day 1. The minimum IP level on Days 2 and 3 was 2.1 mmol/l and 2.0 mmol/l, respectively. In contrast to the remarkable changes in the serum calcium level by PTH treatment, the serum magnesium levels showed few changes. These results indicate that PTH therapy could be effective in correcting serum and urine calcium and the phosphate levels in hypoparathyroidism caused by activating mutation of CaR.

Pregnancy and sarcoidosis: an insight into the pathogenesis of hypercalciuria.

Hypercalciuria with or without hypercalcemia is a well-known complication of sarcoidosis, the pathogenesis of which is not fully understood. Pregnancy is associated with physiologic alterations in calcium metabolism. These changes can further alter the derangement of calcium metabolism that occurs in sarcoidosis, if the two conditions coexist. We had the opportunity to study prospectively the changes in serum and urine calcium along with all the hormonal changes that occur during pregnancy in a young woman with sarcoidosis, who had hypercalciuria at presentation. We believe that an increased level of calcitriol is central to the calcium abnormalities in our patient. In her case, the increased calcitriol is derived from sarcoid granulomas and renal sources enhanced by the effect of estradiol and prolactin on the conversion of 25(OH)D to 1,25(OH)(2) D. She acquired hypoparathyroidism, with normal serum calcium, which probably was due to the direct suppression of parathyroid hormone (PTH) secretion by calcitriol. Finally, hypercalciuria is the result of the combined effect of hyperabsorption of calcium from the gut (the result of increased calcitriol levels leading to increased filtration of calcium) and decreased tubular reabsorption of calcium, as a result of undetectable PTH.

Synthetic human parathyroid hormone 1-34 vs calcitriol and calcium in the treatment of hypoparathyroidism.

OBJECTIVE: To test the hypothesis that treatment with human parathyroid hormone 1-34 (PTH 1-34) can maintain normal serum calcium without hypercalciuria in patients with hypoparathyroidism. DESIGN: Randomized crossover trial lasting 20 weeks. Each 10-week arm consisted of a 2-week inpatient dose-adjustment phase followed by an 8-week outpatient phase. SETTING: Tertiary care center. PATIENTS: A total of 10 patients with hypoparathyroidism were enrolled consecutively over a 15-month period. Half of the patients were prior National Institutes of Health patients, and the other 5 patients were referred from outside physicians. INTERVENTIONS: A dose of PTH 1-34 was administered each morning by subcutaneous injection. Calcitriol was given orally twice daily with supplemental calcium carbonate. MAIN OUTCOME MEASURES: Serum and urine calcium and phosphorus levels. RESULTS: Once-daily treatment with PTH 1-34 maintained serum calcium in the normal range with decreased urine calcium excretion (P<.05 at 2 weeks and P<.Ol at 10 weeks) compared with calcitriol treatment. Biochemical markers of bone turnover increased significantly (P<.Ol at 10 weeks) during PTH 1-34 treatment. CONCLUSIONS: Treatment of hypoparathyroidism with PTH 1-34 reduces urine calcium excretion compared with treatment with calcitriol and calcium.

The relationship between serum intact parathyroid hormone and calcium in idiopathic hypoparathyroidism.

We studied the relationship between serum calcium (Ca) and parathyroid hormone (PTH) in patients with idiopathic hypoparathyroidism (IHP) to investigate the diversity of the degree of parathyroid insufficiency and a regulation of PTH secretion by Ca in IHP. Serum intact PTH concentrations ranged from < 1.0 to 10.3 pg/ml in 20 patients with IHP and were above the detection limit in 18 (90%) patients. Serum total Ca levels in IHP were positively correlated with serum intact PTH (r = 0.824, P < 0.001), in contrast with a negative correlation between serum intact PTH and Ca in 91 normal subjects (r = -0.378, P < 0.001) and abnormally high serum intact PTH values against hypocalcemia in five patients with pseudohypoparathyroidism. In three patients with IHP, serum intact PTH decreased in response to treatment with active vitamin D3 which increased serum Ca and 1,25(OH)2D. An inverse sigmoidal relationship between serum ionized Ca and intact PTH was demonstrated in a patient with IHP before treatment [IHP(-)] and three patients with IHP treated with active vitamin D3[IHP(+)]. Peak serum intact PTH values were reduced in IHP(-) and IHP(+). Baseline serum intact PTH was 77.0% of the maximal level in IHP(-), 51.7-72.1% in IHP(+), and 31.1-42.3% in five normal subjects. The degree of parathyroid dysfunction in IHP differs from one patient to another and serum Ca levels are thought to be determined by circulating PTH levels. Although PTH secretory reserve is diminished, PTH secretion is negatively regulated by Ca and is stimulated at baseline in patients with IHP before and during the treatment with active vitamin D3.

Response of plasma 1,25-dihydroxyvitamin D in the human PTH(1-34) infusion test: an improved index for the diagnosis of idiopathic hypoparathyroidism and pseudohypoparathyroidism.

Synthetic human parathyroid hormone (1-34) (hPTH(1-34] infusion test has been utilized in the differential diagnosis of hypoparathyroidism by examining the incremental response of urinary phosphate and cyclic adenosine monophosphate (AMP). The response of plasma levels of 1,25-dihydroxyvitamin D (1,25(OH)2D) in parathyroid hormone (PTH) infusion test was studied as a new criterion for the differential diagnosis of idiopathic hypoparathyroidism (IHP) and pseudohypoparathyroidism (PHP). Fourteen patients with IHP, 4 patients with PHP, and five control subjects were studied. All subjects received an intravenous infusion of 30 micrograms hPTH(1-34) over 5 minutes. The basal levels of plasma 1,25(OH)2D in patients with IHP and PHP were significantly lower than those in control subjects, but there was no significant difference between the levels in patients with IHP and in patients with PHP. The plasma levels of 1,25(OH)2D increased after the infusion of hPTH(1-34) and reached a peak 6 to 24 hours afterward. The 1,25(OH)2D increase at 24 hours afterward the infusion (delta 1,25(OH)2D) in control subjects and in patients with IHP were 18.1 +/- 3.91 (mean +/- SEM) and 24.1 +/- 2.80 pg/ml, respectively. There was no significant increase in patients with PHP (delta 1,25(OH)2D = 4.9 +/- 1.97 pg/ml). From these results, the measurement of delta 1,25(OH)2D in hPTH(1-34) infusion test is useful as a criterion for the differential diagnosis of hypoparathyroidism.

Synthetic human parathyroid hormone-(1-34) for the study of pseudohypoparathyroidism.

The synthetic amino-terminal fragment of PTH, PTH-(1-34), was recently released for clinical testing of PTH responsiveness. We measured the urinary cAMP and phosphaturic responses to infusion of PTH-(1-34) [3U/kg BW (200 U maximum), iv in 10 min] in patients with pseudohypoparathyroidism and idiopathic hypoparathyroidism, as well as normal subjects. The protocol used data from 5 30-min urine collections and 4 blood samples. Based on the results in 7 patients with pseudohypoparathyroidism (hypocalcemia with increased serum immunoreactive PTH concentrations), 2 patients with suspected pseudohypoparathyroidism, 9 patients with surgical hypoparathyroidism, and 10 normal subjects, this testing protocol differentiated well among these conditions. The patients with pseudohypoparathyroidism had blunted cAMP and phosphaturic responses to PTH-(1-34) administration compared to those of either normal or hypoparathyroid subjects. Induced hypercalcemia failed to restore a normal cAMP response to PTH-(1-34) infusion in 2 patients with pseudohypoparathyroidism. Calculation of the cAMP response to PTH-(1-34) as nanomoles per dL glomerular filtrate during the first 30 min after infusion provided better differentiation among groups than other parameters of cAMP metabolism. Calculating the phosphaturic response as the percent fall in tubular maximum for phosphate reabsorption during the first hour after infusion gave the best degree of statistical separation among groups. We conclude that this new diagnostic agent is effective for the study of renal responsiveness to PTH, and that the protocol described here reliably differentiates patients with pseudohypoparathyroidism from those with hypocalcemia due to other causes.

Effect of intravenous glucagon on the urinary excretion of adenosine 3',5'-monophosphate in man and in rats. Evidence for activation of renal adenylate cyclase and formation of nephrogenous cAMP.

To examine the effect of glucagon in vivo on renal formation and excretion of cAMP, clearance studies were performed in patients with hypoparathyroidism and in parathyroidectomized rats. Four patients with idiopathic hypoparathyroidism and 2 patients with pseudohypoparathyroidism were studied during an intravenous glucagon infusion (20 micrograms/kg body weight). In all patients, glucagon induced a significant increase in nephrogenous cAMP and a 2- to 3-fold increase in fractional excretion of phosphate. The average increase in nephrogenous cAMP was from a baseline of 784 +/- 229 to 18,748 +/- 3,842 pmol/100 ml glomerular filtrate (GF) (p less than 0.01) and occurred 30-60 min after the beginning of the glucagon infusion. The effect of intravenous glucagon, given as a bolus, was further examined in parathyroidectomized rats. Glucagon elicited a significant increase in the urinary excretion of the nucleotide. The excreted cAMP was compared with its filtered load for each urine collection period. In the first two collections, 0-15 and 15-30 min, the filtered load of cAMP was higher than its urinary excretion. During the following periods, 30-90 min, the excreted urinary cAMP exceeded by far its filtered load, suggesting a net nephrogenous contribution to the excretion of the nucleotide. Infusion of exogenous cAMP to parathyroidectomized rats induced significant increments in the filtered load and urinary excretion of the nucleotide. Tubular secretion of extrarenal cAMP could not be detected during the cAMP infusion. These results provide evidence supporting in vivo a possible parathyroid-independent formation of nephrogenous cAMP after glucagon administration, in men and in rats. The glucagon-induced increase in nephrogenous cAMP seems to account, at least partly, for some of the renal actions of this hormone.

A 6-hour human parathyroid hormone (1-34) infusion protocol: studies in normal and hypoparathyroid subjects.

Parathyroid hormone (PTH)-resistant states are usually diagnosed by the failure of an acute PTH injection to elicit a rise in urinary cAMP and phosphate or, less commonly, by the failure of repeated PTH injections to raise serum calcium. We have established a 6 hour infusion of human PTH (1-34) which identifies PTH-resistant hypoparathyroid subjects on the basis of serum 1,25-dihydroxyvitamin D (1,25(OH)2D) and calcium responses. 1,25-Dihydroxyvitamin D levels increased by at least 58 pmol/liter and serum calcium by at least 0.1 mmol/liter in PTH-responsive hypoparathyroid subjects (n = 6), whereas in pseudohypoparathyroid subjects (n = 5) these levels rose by less than 22 pmol/liter and 0.06 mmol/liter respectively. The responsiveness of urinary phosphate excretion, expressed as the renal threshold phosphate concentration (TmPO4/GFR), to PTH also clearly separated the pseudohypoparathyroid patients from the other subjects. Differences in urinary calcium responses were observed though this parameter was less reliable in the identification of individual PTH-resistant or PTH-sensitive hypoparathyroid patients. Nephrogenous cAMP did not discriminate between groups when this protocol was used. This test has the potential to facilitate and extend the classification of PTH-resistant states.

[Standard procedure and the diagnostic criteria for the Ellsworth-Howard test using human PTH-(1-34)].

The present study was undertaken to establish a standard method to perform the Ellsworth-Howard test using human PTH-1-34). For this purpose we made a survey of literature concerning the Ellsworth-Howard test and then examined the data of the Ellsworth-Howard tests performed on 178 hypoparathyroid patients using human PTH-(1-34). The main items of investigation were: (i) to determine the appropriate dose of PTH for administration to adults and children; and (ii) to define the criteria of practical usefulness for the differential diagnosis of the types of hypoparathyroidism. From the analysis of the data, the following findings and conclusions were obtained. The dose of human PTH-(1-34) appropriate for diagnostic use is 100 U per person for adults and 100 U per body surface area of one square meter (100 U/m2) for children. The criteria of positive response in the Ellsworth-Howard test are defined as follows. a) phosphaturic response: (U4 + U5) - (U2 + U3) = more than 35 mg/2 h b) cyclic AMP response: U4 - U3 = more than 1 mumol/h, and U4/U3 = more than 10 times. In the above formula, U2 - U5 represent the urine samples collected hourly in order. PTH is injected at the time between U3 and U4. For the application of the criteria in children, one should use the values corrected for body surface area of one square meter. It is necessary to confirm the following conditions before the application of the criteria: the presence of hypocalcemia and hyperphosphatemia; the lack of phosphate deficiency (basal urinary phosphate excretion more than 10 mg/2 h); the accuracy of timed urine collections (ratio of creatinine excretion during 2 hours before PTH to that after PTH administration in the range from 0.8 to 1.2); and the absence of marked diurnal variation in phosphate excretion (difference in phosphate excretion between the two basal hourly urine less than 17.5 mg/h). To ensure the above conditions, medications such as phosphate-binding antacids should be withheld for at least 1 week before the test, and the test should be performed according to the standard procedure described in this paper. The diagnosis of pseudohypoparathyroidism Type II should be done cautiously. It is necessary to take account of the high basal urinary cyclic AMP excretion and the elevated serum PTH level along with the results of the Ellsworth-Howard test (positive cyclic AMP response and negative phosphaturic response) for a definite diagnosis of this entity.

Differentiation of pseudo- and idiopathic hypoparathyroidism by measuring urinary calcitonin.

Calcitonin (CT) levels were determined in urine specimens from normal subjects and patients with pseudohypoparathyroidism type I (PHP), idiopathic hypoparathyroidism (IHP), pseudopseudohypoparathyroidism (PPHP), and surgical hypoparathyroidism (SHP). Urinary CT was measured by RIA after extraction of urine by gel chromatography on a 0.8 X 20-cm column of Bio-Gel P-2. The urinary CT level ranged from 420-1000 pg/mg creatinine (Cr; mean +/- SD, 631 +/- 229) in PHP (n = 6), from 50-270 (131 +/- 92) in IHP (n = 6), and from 35-93 (66 +/- 27) in SHP (n = 6), and was 185 pg/mg Cr in one patient with PPHP. The mean value in PHP was significantly (P less than 0.001) higher, and that in SHP was significantly (P less than 0.05) lower, than those in the age-matched normal subjects. In each patient with PHP and IHP before and after treatment with 1 alpha-hydroxycholecalciferol, urinary CT levels fluctuated between 700-1370 pg/mg Cr in PHP and from 43-195 pg/mg Cr in IHP. Increased urinary excretion of CT in patients with PHP suggests that CT secretion may be enhanced in this disease. The biological role of CT in PHP remains to be clarified.

Calcium potentiates the cyclic nucleotide and phosphaturic response to parathyroid hormone infusion.

To determine whether calcium modulates the action of PTH, we measured the cyclic nucleotide and phosphaturic response to PTH following a 4-h infusion of glucose (day 1) and calcium (day 2). The 12 subjects were selected to provide a range of low, normal, and high endogenous PTH function. PTH stimulated nephrogenous cAMP [185 +/- 31 nmol/100 ml glomerular filtrate (GF)], cyclic guanosine monophosphate (0.44 +/- 0.09 mumol/g creatinine), and phosphate (367 +/- 59 mg P/g creatinine) excretion. Calcium infusion stimulated nephrogenous cAMP excretion in the hypoparathyroid subjects (1.42 +/- 0.35 nmol/100 ml GF) but reduced it in subjects with normal parathyroid function (-2.22 +/- 0.46 nmol/100 ml GF). Calcium infusion stimulated cGMP (0.64 +/- 0.1 mumol/g creatinine) and phosphate (113 +/- 48 P/g creatinine) excretion in all subject groups. Calcium infusion led to a 2-fold increase in the cyclic nucleotide and phosphaturic response to PTH in the normal and hypoparathyroid subjects, but had little effect on the PTH response in hyperparathyroid subjects. The extent to which calcium potentiated the ability of PTH to stimulate nephrogenous cAMP excretion correlated negatively with the basal nephrogenous cAMP excretion (r = -0.685, P less than 0.01). We conclude that calcium potentiates the acute effects of PTH on renal cyclic nucleotide and phosphate excretion. This effect is modified by the basal levels of PTH stimulation of the kidney such that it is reduced in magnitude when basal PTH stimulation is increased.

[The diuresis of cyclic adenosine-3'5'-monophosphate (cAMP) in primary and secondary disorders of the parathyroid glands]. / Die Diurese von zyklischem Adenosin-3'5'-monophosphat (cAMP) bei primären und Sekundären Funktionsstörungen der Nebenschilddrüsen.

The diuresis of cAMP in primary hyperparathyroidism was significantly higher at 7.3 +/- 2.5 mumol/g creatinine X 24 h (P less than 0.005) than that in healthy subjects (3.5 +/- 0.7 mumol/g creatinine X 24 h). After successful operation on the parathyroid gland, cAMP diuresis usually decreased within 24 hours to normal or subnormal values. In primary or secondary hypoparathyroidism subnormal amounts of cAMP (P less than 0.005) were excreted. The method gives false-negative results in functional disorders of the parathyroid glands accompanied or caused by renal failure.

Urinary oxalate on a high-oxalate diet as a clinical test of malabsorption.

100 g of spinach a day was added to the hospital diet of fifty-four patients with suspected malabsorption. Hyperoxaluria was found in thirty-eight patients; all of them had steatorrhoea. No patient with steatorrhoea had a urinary oxalate excretion of less than 40 mg a day. Ten other patients had hyperoxaluria, but the faecal fat determinations were regarded as unreliable in almost all and malabsorption could not be confirmed. It is suggested that in clinical practice determination of urinary oxalate after an oral load of oxalate could replace faecal fat determination in most patients with suspected malabsorption.