Self-reported calcium use in a cohort of postmenopausal women receiving osteoporosis therapy: results from POSSIBLE US™

Calcium use was common and remained high among women on osteoporosis therapy. Use of calcium-supplemented pharmacologic therapy increased from 65.1 to 76.0% in these women (mean follow-up, 27.5 months). Over 12 months, calcium discontinuation was fairly similar among women using calcium only (23.7%) and women supplementing pharmacologic therapy with calcium (22.5%).

INTRODUCTION

Calcium has an important role in bone health. This study describes calcium use and persistence in a postmenopausal osteoporosis treatment cohort.

METHODS

Subject-reported calcium use was analyzed for 3,722 participants of the Prospective Observational Scientific Study Investigating Bone Loss Experience (POSSIBLE US(TM)) who used calcium either as their sole osteoporosis treatment (calcium only) or to supplement pharmacologic osteoporosis therapy (supplementers). Descriptive analyses were conducted. Kaplan-Meier methods were used to estimate the probability of discontinuing calcium therapy, and logistic regression was used to assess associations (age-adjusted odds ratios) between healthy behaviors and calcium use.

RESULTS

At entry, there were 711 calcium-only subjects and 1,960 of 3,011 subjects on pharmacologic osteoporosis therapy also supplementing with calcium (supplementers). The percentage of supplementers increased from 65.1 to 76.0% during follow-up (mean, 27.5 months). During the first 12 months on study, the probability of calcium discontinuation was 23.7% (95 % confidence interval [CI], 20.7 - 27.0) among calcium-only subjects and 22.5% (95% CI, 20.7-24.5) among supplementers. Supplementers who discontinued pharmacologic therapy were more likely to discontinue calcium than supplementers who continued pharmacologic therapy (34.9 versus 14.8%). Overall 54.2% of calcium-only subjects who discontinued calcium and 42.3% of supplementers who discontinued calcium resumed calcium use during follow-up. Regular exercise was positively correlated with calcium use at study entry.

CONCLUSIONS

Calcium supplementation in pharmacologically treated subjects increased over time. Persistence with calcium was high. Discontinuation of pharmacologic osteoporosis therapy was associated with an increased likelihood of discontinuing calcium use.

Persistence and switching patterns among women with varied osteoporosis medication histories: 12-month results from POSSIBLE US

During the first year of Prospective Observational Scientific Study Investigating Bone Loss Experience (POSSIBE US), many women transitioned (i.e., discontinued or switched) from their baseline osteoporosis medication. Participants not on stable therapy at entry, with side effects, and with poor physical status were at higher risk of transitioning. Understanding factors associated with persistence may lead to improved outcomes.

INTRODUCTION

Postmenopausal osteoporosis (PMO) medication use patterns may differ by treatment history and drug class. We describe these patterns among patients in primary care settings using patient-reported data.

METHODS

Data from 3,006 participants of the POSSIBLE US were used to estimate the probability of a baseline PMO medication transition (i.e., discontinuation or switch) and hazard ratios (HRs) for predictors of these transitions.

RESULTS

One year after study entry, the probability of persisting with a baseline medication was 66% (95% CI: 64-68%). After adjusting for age and osteoporosis diagnosis, factors at entry independently associated with a higher risk of baseline medication transition were treatment status cohort, side effect severity, and OPAQ-SV physical function score. Compared to participants stable on therapy at entry, others had a higher risk, ranging from HR = 1.59 (95% CI: 1.36-1.85) for those new to therapy to HR = 2.00 (95% CI: 1.27-3.15) for those who recently augmented therapy at entry. Participants reporting moderate (HR = 1.31, 95% CI: 1.09-1.57) or severe (HR = 1.88, 95% CI: 1.49-2.39) side effects had a higher risk than those not reporting side effects. Participants reporting Osteoporosis Assessment Questionnaire-Short Version physical function scores in the lowest tertile had a higher risk (HR = 1.27, 95% CI: 1.07-1.52) than those reporting scores in the highest tertile.

CONCLUSION

Baseline osteoporosis medication transitions were common in the first year of POSSIBLE US. Participants not on stable therapy at entry, or who reported severe side effects, or had poor physical health status were at higher risk for these transitions.

Effects of arzoxifene on bone, lipid markers, and safety parameters in postmenopausal women with low bone mass

In this Phase 2 study of postmenopausal women with low bone, arzoxifene (a selective estrogen receptor modulator (SERM)) significantly reduced bone turnover marker levels and increased bone mineral density (BMD) versus placebo. Arzoxifene generally had greater effects on bone turnover and BMD than raloxifene, a SERM in current clinical use. Arzoxifene's safety profile appeared similar to raloxifene.

INTRODUCTION

This 6-month, Phase 2, double-blind, placebo- and raloxifene-controlled study was designed to assess the effects of arzoxifene on bone turnover and overall safety in postmenopausal women with low bone mass.

METHODS

Postmenopausal women (N = 219; mean age, 59 years) with a T-score between -1 and -2.5 were randomly assigned to daily arzoxifene 5, 10, 20, or 40 mg, raloxifene 60 mg, or placebo. All received daily calcium.

RESULTS

All arzoxifene doses significantly reduced osteocalcin (primary endpoint), type 1 collagen C-telopeptide, bone specific alkaline phosphatase, and procollagen type I amino-terminal propeptide versus placebo, and increased lumbar spine BMD. Arzoxifene generally had greater effects on bone turnover and BMD than raloxifene. Arzoxifene decreased cholesterol, low-density lipoprotein cholesterol, and fibrinogen versus placebo. Endometrial thickness change with arzoxifene was not significantly different from placebo or raloxifene; no cases of endometrial hyperplasia or adenocarcinoma were observed. Adverse event reporting with arzoxifene was similar to that with raloxifene, as were hot flush and night sweat reporting.

CONCLUSIONS

Arzoxifene suppressed bone turnover and increased BMD. Within the limitations of this study, the endometrial safety profile of arzoxifene appeared similar to that of raloxifene. While no clear dose effect was evident, arzoxifene 20 and 40 mg/day appeared the optimal doses for reducing bone turnover.

Comparison of alendronate and intranasal calcitonin for treatment of osteoporosis in postmenopausal women

This study compared the effects of oral alendronate and intranasal calcitonin for treatment of osteoporosis in postmenopausal women. Women at least 5 yr postmenopause (n = 299) were randomized to either 10 mg alendronate, matching alendronate placebo, or open-label intranasal calcitonin 200 IU daily for 12 months. Hip and spine bone mineral density (BMD) and markers of bone turnover were measured, and safety and tolerability were assessed. Alendronate produced greater increases in BMD than calcitonin at 12 months at the lumbar spine (5.16% vs. 1.18%; P < 0.001), trochanter (4.73% vs. 0.47%; P < 0.001), and femoral neck (2.78% vs. 0.58%; P < 0.001). Changes in BMD with calcitonin were greater than with placebo at the femoral neck, but were not different from placebo at either the trochanter or lumbar spine. Greater decreases in bone turnover were seen with alendronate than with calcitonin (serum bone-specific alkaline phosphatase, 43% vs. 9%, P < 0.001; urinary N-telopeptide, 62% vs. 11%, P < 0.001). Similar percentages of patients in each group reported an adverse experience during the study. We conclude that, in postmenopausal women with osteoporosis, 12 months of therapy with alendronate produced significantly greater increases in BMD of the hip and spine and greater decreases in bone turnover than intranasal calcitonin.

Alendronate and estrogen effects in postmenopausal women with low bone mineral density. Alendronate/Estrogen Study Group

The bisphosphonate alendronate and conjugated equine estrogens are both widely used for the treatment of postmenopausal osteoporosis. Acting by different mechanisms, these two agents decrease bone resorption and thereby increase or preserve bone mineral density (BMD). The comparative and combined effects of these medications have not been rigorously studied. This prospective, double blind, placebo-controlled, randomized clinical trial examined the effects of oral alendronate and conjugated estrogen, in combination and separately, on BMD, biochemical markers of bone turnover, safety, and tolerability in 425 hysterectomized postmenopausal women with low bone mass. In addition, bone biopsy with histomorphometry was performed in a subset of subjects. Treatment included placebo, alendronate (10 mg daily), conjugated equine estrogen (CEE; 0.625 mg daily), or alendronate (10 mg daily) plus CEE (0.625 mg daily) for 2 yr. All of the women received a supplement of 500 mg calcium daily. At 2 yr, placebo-treated patients showed a mean 0.6% loss in lumbar spine BMD, compared with mean increases in women receiving alendronate, CEE, and alendronate plus CEE of 6.0% (P < 0.001 vs. placebo), 6.0% (P < 0.001 vs. placebo), and 8.3% (P < 0.001 vs. placebo and CEE; P = 0.022 vs. alendronate), respectively. The corresponding changes in total proximal femur bone mineral density were +4.0%, +3.4%, +4.7%, and +0.3% for the alendronate, estrogen, alendronate plus estrogen, and placebo groups, respectively. Both alendronate and CEE significantly decreased biochemical markers of bone turnover, specifically urinary N-telopeptide of type I collagen and serum bone-specific alkaline phosphatase. The alendronate plus CEE combination produced slightly greater decreases in these markers than either treatment alone, but the mean absolute values remained within the normal premenopausal range. Alendronate, alone or in combination with CEE, was well tolerated. In the subset of patients who underwent bone biopsies, histomorphometry showed normal bone histology with the expected decrease in bone turnover, which was somewhat more pronounced in the combination group. Thus, alendronate and estrogen produced favorable effects on BMD. Combined use of alendronate and estrogen produced somewhat larger increases in BMD than either agent alone and was well tolerated.

An open-label extension study of alendronate treatment in elderly women with osteoporosis

We have recently reported the results of a 24-month, double-blind, placebo-controlled study in 359 elderly osteoporotic women who were treated with daily oral alendronate (ALN) 1, 2.5, or 5 mg or placebo (PBO). We report the results of a 12-month, open-label, extension study during which 246 patients from the original study were treated with ALN 10 mg/day. Significant increases in lumbar spine bone mineral density (BMD) were observed in patients who had previously received PBO or ALN 1 and 2.5 mg/day for 24 months. Significant gains in trochanter BMD were seen in all treatment groups. Small changes were observed in femoral neck, total body, and forearm BMD during the course of this extension study. In general, the greatest increases in BMD during the open-label extension year occurred in patients who received either PBO or the lower doses of ALN during the previous 2-year blinded study. The frequencies of all categories of upper gastrointestinal adverse experiences (AEs) were less during months 25-36 (open-label extension) than during months 0-24 (original study). In conclusion, treatment with ALN 10 mg/day for 12 months in elderly women with osteoporosis who were previously treated for 24 months with PBO or ALN 1, 2.5, or 5 mg/day increased or maintained BMD of the spine, trochanter, and forearm, and was generally safe and well tolerated, especially in the upper gastrointestinal tract.

Variations in physicians' judgments about corticosteroid induced osteoporosis by physician specialty

OBJECTIVE

Longterm corticosteroid use is associated with an increased risk of osteoporosis and fractures. Calcium and vitamin D supplementation and estrogen replacement therapy can decrease this risk, but the majority of patients receiving longterm corticosteroid treatment do not receive treatments to prevent bone loss. We assess whether this is due to variations in physicians' judgments about risks and efficacy of treatments to prevent corticosteroid-induced osteoporosis.

METHODS

Questionnaires were mailed to 425 physicians, who were sampled so that half were generalists and half were specialists. Physicians were given hypothetical clinical scenarios involving patients taking corticosteroids and asked to judge the importance of osteoporosis as a risk of corticosteroid treatment, the importance of discussing this side effect with patients, and to indicate how often they would use calcium with vitamin D and estrogen for a hypothetical postmenopausal patient receiving longterm corticosteroid treatment.

RESULTS

In total 198 physicians (50%) responded to this survey. Most physicians rated osteoporosis as one of the 3 most significant side effects of corticosteroid treatment for postmenopausal women, but there was significant variation in physician judgments about the importance of corticosteroid induced osteoporosis for premenopausal women (p=0.03) and men (p=0.001). There was also significant variation in physician judgments about the importance of discussing osteoporosis as a side effect with patients (p=0.001), and their use of both calcium and vitamin D (p=0.002) and estrogen replacement therapy (p=0.001) for a hypothetical postmenopausal patient. The physician characteristics most associated with these differences were physician specialty and experience with corticosteroid use. Primary care physicians and physicians who more commonly prescribe corticosteroids were more likely to report that they would use estrogen and calcium to prevent corticosteroid induced bone loss. Physician age, sex, and university affiliation had no association with physician assessments.

CONCLUSION

Physicians' judgments varied significantly by physician specialty and experience with corticosteroid use. These data suggest that patients cared for by physicians in different specialties will get varying advice about osteoporosis risk and preventive treatments when receiving longterm corticosteroid treatment.

Dose-response relationships for alendronate treatment in osteoporotic elderly women. Alendronate Elderly Osteoporosis Study Centers

Alendronate (ALN) is an aminobisphosphonate employed as an antiresorptive agent in the treatment of osteoporosis. The present study was carried out to determine dose-response relationships, particularly the effects of relatively low doses of ALN, on bone mineral density (BMD), biochemical indexes of bone and mineral metabolism, and bone histology, with particular attention to effects in elderly women. This prospective, randomized, double blind, 2-yr multicenter study compared the effects of placebo with those of 1.0, 2.5, or 5.0 mg ALN daily. All subjects received supplemental calcium (500 mg daily) as the carbonate. We studied 359 women with lumbar spine BMD at least 2.0 SD below the peak young adult mean. Subjects were stratified by age, with 135 aged 60-69 yr and 224 aged 70-85 yr. Histomorphometry was performed on transiliac bone biopsies obtained from 104 subjects after 1 yr and from 83 subjects after 2 yr. This study elucidated the previously uninvestigated lower region of the dose-response curve for ALN in osteoporosis. Over 2 yr, treatment with 1.0, 2.5, or 5.0 mg/day increased lumbar spine BMD, on the average, by 0.65%, 3.54%, and 5.67%, respectively, compared with that in the placebo group (P < 0.001 vs. placebo for the 2.5 and 5 mg groups). Significant dose-related increases were also seen in BMD at appendicular sites and in total body BMD. Dose-dependent reductions in bone turnover to new steady states were indicated by serum and urine biochemical markers as well as by histomorphometry. There was also a dose-related reduction in the proportion of subjects suffering nonvertebral fractures (P < 0.05). Safety profiles were similar for the ALN and placebo groups and for both age strata. Efficacy was similar for both age strata. There was no evidence of impaired mineralization or other histological abnormalities due to ALN treatment. We conclude that treatment with ALN over a period of 2 yr was well tolerated and produced dose-dependent increases in BMD without evidence of a plateau over the dose range of 1.0-5.0 mg daily. One milligram daily did not result in a significant effect on BMD, and 5.0 mg daily produced favorable effects at all sites measured. Other studies have demonstrated somewhat greater effects on 10 mg daily. ALN, was equally effective and well tolerated in osteoporotic women over 70 yr old as in younger women with the same condition.

Effect of oral alendronate on bone mineral density and the incidence of fractures in postmenopausal osteoporosis. The Alendronate Phase III Osteoporosis Treatment Study Group

BACKGROUND

Postmenopausal osteoporosis is a serious health problem, and additional treatments are needed.

METHODS

We studied the effects of oral alendronate, an aminobisphosphonate, on bone mineral density and the incidence of fractures and height loss in 994 women with postmenopausal osteoporosis. The women were treated with placebo or alendronate (5 or 10 mg daily for three years, or 20 mg for two years followed by 5 mg for one year); all the women received 500 mg of calcium daily. Bone mineral density was measured by dual-energy x-ray absorptiometry. The occurrence of new vertebral fractures and the progression of vertebral deformities were determined by an analysis of digitized radiographs, and loss of height was determined by sequential height measurements.

RESULTS

The women receiving alendronate had significant, progressive increases in bone mineral density at all skeletal sites, whereas those receiving placebo had decreases in bone mineral density. At three years, the mean (+/- SE) differences in bone mineral density between the women receiving 10 mg of alendronate daily and those receiving placebo were 8.8 +/- 0.4 percent in the spine, 5.9 +/- 0.5 percent in the femoral neck, 7.8 +/- 0.6 percent in the trochanter, and 2.5 +/- 0.3 percent in the total body (P < 0.001 for all comparisons). The 5-mg dose was less effective than the 10-mg dose, and the regimen of 20 mg followed by 5 mg was similar in efficacy to the 10-mg dose. Overall, treatment with alendronate was associated with a 48 percent reduction in the proportion of women with new vertebral fractures (3.2 percent, vs. 6.2 percent in the placebo group; P = 0.03), a decreased progression of vertebral deformities (33 percent, vs. 41 percent in the placebo group; P = 0.028), and a reduced loss of height (P = 0.005) and was well tolerated.

CONCLUSIONS

Daily treatment with alendronate progressively increases the bone mass in the spine, hip, and total body and reduces the incidence of vertebral fractures, the progression of vertebral deformities, and height loss in postmenopausal women with osteoporosis.

Mild vitamin D deficiency and secondary hyperparathyroidism in nursing home patients receiving adequate dietary vitamin D

OBJECTIVE

To compare the vitamin D metabolite and nutritional status of institutionalized elderly males with a noninstitutionalized control group.

DESIGN

Case-control study.

SETTING

Veterans Administration Medical Center Nursing Home (NH) in Richmond, Virginia.

PATIENTS

Fifty-seven consecutive nursing home subjects were screened. After excluding blacks, those receiving anticonvulsants, glucocorticoids, or vitamin supplements, and those with liver or renal failure (creatinine greater than 1.5 mg/dL), 35 subjects were enrolled, and 22 completed the study. The noninstitutionalized control group (n = 18) consisted of consecutive volunteers, meeting the above criteria, from either a senior citizen group or a geriatric clinic.

MEASUREMENTS AND MAIN RESULTS

The serum 25-hydroxy-vitamin D level in the NH residents was significantly lower than in community dwellers (17.4 +/- 5.2 ng/mL vs 31.2 pg/mL +/- 8.0 ng/mL, P less than 0.0001). No significant difference was demonstrated in 1,25-dihydroxyvitamin D levels (36.5 pg/mL +/- 10.5 in NH residents vs 42.0 pg/mL +/- 11.1 in controls). In the NH group PTH levels were inversely correlated with 25 OHD levels (P less than 0.008) and positively correlated with length of stay in the NH (P less than 0.016). There was no significant seasonal variation in vitamin D metabolite levels in the NH group. In the NH patients, the mean dietary intake of vitamin D was 232 +/- 378 mg/day and of calories was 1811 +/- 447 kcal/day.

CONCLUSION

Despite apparently adequate calories, calcium, and vitamin D intake, hypovitaminosis D with compensatory PTH elevations occurs, regardless of season, in the nursing home population.

Glucocorticoids decrease vitamin D receptor number and gene expression in human osteosarcoma cells

The mechanisms by which glucocorticoids (GC) inhibit some actions of vitamin D [1,25-(OH)2D3] are not well understood, but there is growing evidence that GC alter vitamin D receptor (VDR) number. We studied the effects of dexamethasone (DEX) on VDR number and mRNA in the human osteosarcoma cell line, MG-63. The effects of DEX on 1,25-(OH)2D3 binding were examined by incubating confluent cells overnight in media without or with 10(-6) M DEX. DEX decreased VDR number (B max) by approximately 70% (110 versus 32 fmol/mg cellular protein, p less than 0.001) without significantly changing the apparent affinity (K'D) of 1,25-(OH)2D3 for its receptor (3.8 versus 2.2 x 10(-10) M, p greater than 0.05). Overnight incubation of MG-63 cells with DEX produced a time- and dose-responsive decrease in VDR mRNA compared to untreated controls (p less than 0.01). To determine the mechanism of the DEX-mediated decrease in VDR mRNA, the effect of DEX on VDR mRNA stability was studied. We found that the half-life for the VDR mRNA was approximately 5.7 h and was not significantly changed when the cells were incubated with DEX (approximately 6.3 h). We conclude that DEX decreases both VDR number and mRNA in MG-63 osteosarcoma cells. Since the half-life of VDR mRNA was not significantly modified by dexamethasone, glucocorticoids appear to decrease VDR mRNA by inhibiting VDR gene transcription or by affecting the processing of VDR mRNA.

New form of pseudohypoparathyroidism with abnormal catalytic adenylate cyclase

Patients with pseudohypoparathyroidism type Ia have resistance to multiple hormones because of deficient activity of the stimulatory guanine nucleotide-binding protein (Gs) that couples membrane receptors to activation of adenylate cyclase. However, in a subset of patients with pseudohypoparathyroidism who have resistance to multiple hormones yet possess normal erythrocyte membrane Gs activity, the biochemical abnormality responsible for hormone resistance has remained undefined. Cultured skin fibroblasts were derived from a patient with this atypical form of pseudohypoparathyroidism. In the patient's fibroblast membranes, adenylate cyclase stimulation mediated by Gs after fluoride ion treatment produced only 52% of normal activity, yet fibroblast membrane Gs activity measured by cyc- complementation was normal. Activation of the catalytic unit of adenylate cyclase with manganese produced 49% of normal activity; manganese plus forskolin produced 54% of normal adenylate cyclase activity. beta-Adrenergic receptor coupling to Gs and phosphodiesterase activity were normal. A defect in the catalytic unit of adenylate cyclase can account for these results and may be a mechanism for clinical resistance to multiple hormones that act through adenylate cyclase.

Cushing's disease in two sisters

Hereditary Cushing's syndrome is an uncommon clinical entity, and most reported cases have been described in families with nodular adrenocortical dysplasia. Isolated cases of Cushing's disease (pituitary-dependent bilateral adrenal hyperplasia) have been reported in association with the multiple endocrine neoplasia syndrome, Type I (MEN I), but there are no published reports of pedigrees with more than one affected family member. Within a period of 8 months, two sisters presented with clinical findings suggestive of hypercortisolism, and Cushing's disease was confirmed by appropriate diagnostic studies. There was no evidence of any other endocrine excess syndrome in either patient. Transsphenoidal pituitary surgery confirmed the presence of an ACTH-immunostaining pituitary adenoma in each woman. The authors think this is the first report in the English literature of Cushing's disease in first-degree relatives.

Cyclic nucleotides regulate collagen production by human intestinal smooth muscle cells

The effect of cyclic nucleotides on collagen production by human intestinal smooth muscle cells was examined in vitro. Cholera toxin and isobutylmethylxanthine, agents that elevate cyclic adenosine monophosphate, caused selective inhibition of collagen production when cells were exposed to these agents for 24-72 h. Exposure for 6 h inhibited noncollagen protein synthesis without effects on collagen production. Forskolin similarly inhibited collagen production, decreasing relative collagen synthesis 40% at 10 microM and 60% at 100 microM. After 48 h of exposure to cholera toxin and isobutylmethylxanthine, levels of cyclic adenosine monophosphate had increased in a concentration-dependent manner. The effect of cyclic nucleotide analogues was also examined. Dibutyryl cyclic adenosine monophosphate inhibited collagen production, whereas dibutyryl cyclic guanosine monophosphate increased collagen production by 65%. This effect was maximal at a concentration of 10 microM. These observations suggest that cyclic adenosine monophosphate has a significant effect on collagen production by human intestinal smooth muscle cells in vitro and may play a role in the modulation of collagen production by these cells in vivo.

Effect of short-term glucocorticoids on serum osteocalcin in healthy young men

Young healthy men were studied during brief treatment with prednisone to determine the rapidity of the effects of glucocorticoids on serum osteocalcin. Seven subjects were given 60 mg of prednisone orally at 8 a.m. on 5 consecutive days. Serum osteocalcin fell to 68% of the pretreatment level within 24 hours after the first dose was administered (p less than 0.01) and reached a nadir of 37% of baseline between 48 and 96 hours after treatment was begun (p less than 0.005). When prednisone was discontinued, serum osteocalcin returned promptly to pretreatment levels. Similar, though less marked, effects were found with lower doses of prednisone. Serum osteocalcin was not different from baseline after 5 mg of prednisone in five subjects, but after treatment of five subjects each with 10, 15, or 20 mg of prednisone, osteocalcin levels were 83%, 78%, and 74% of baseline, respectively (p less than 0.05). Serum osteocalcin levels fell rapidly with glucocorticoid administration, indicating that the effects of glucocorticoids on bone cells may be demonstrated long before clinical evidence of osteoporosis becomes apparent.

Cushing's syndrome resulting from primary pigmented nodular adrenocortical disease

In a 10-year-old boy with Cushing's syndrome, the dexamethasone suppression test, the metyrapone test, and both basal and corticotropin-releasing factor-stimulated corticotropin levels all indicated a primary adrenal disorder. However, a computed tomographic scan failed to detect an adrenal tumor. At surgery, the adrenal glands were not enlarged but were studded with small pigmented nodules composed of enlarged nonmalignant adrenocortical cells. This unusual abnormality, referred to as primary pigmented nodular adrenocortical disease, is associated with autonomous hypersecretion of cortisol primarily in children and young adults. Our patient was cured by total bilateral adrenalectomy and corticosteroid replacement therapy, the treatment of choice for this condition.

Potentiation by glucose of lipolytic responsiveness of human adipocytes

The effect of glucose on lipolytic regulation was studied in isolated human adipocytes. Glucose enhanced adipocyte glycerol release in the presence and absence of the beta-adrenergic agent ritodrine by 150-200% of control rates. The glucose effect was maximal at just greater than 1 mM glucose and could not be attributed to prevention of a time-dependent decline in lipolysis. Glucose not only increased lipolytic stimulation at each of several concentrations of ritodrine but also enhanced the sensitivity to stimulation at low concentrations of the agent. Ritodrine-stimulated lipolysis was inhibited by insulin by 50-60%; although glucose increased absolute rates of lipolysis, it did not affect the relative inhibition of lipolysis by insulin or the sensitivity to the hormone. In investigating a possible cause of the glucose effect on lipolysis, it was found that the addition of adenosine deaminase increased lipolytic rates in the absence of glucose and blunted the relative stimulation of lipolysis by glucose, the latter implicating extracellular adenosine in the mechanism of the glucose effect.

Activity of the stimulatory guanine nucleotide-binding protein is reduced in erythrocytes from patients with pseudohypoparathyroidism and pseudopseudohypoparathyroidism: biochemical, endocrine, and genetic analysis of Albright's hereditary osteodystrophy in six kindreds

Multiple hormone resistance in many patients with pseudohypoparathyroidism (PHP) type Ia and Albright's hereditary osteodystrophy (AHO) is associated with deficient activity of the stimulatory guanine nucleotide-binding protein (Gs) of adenylate cyclase. To study further the relationship of deficient Gs activity to hormone resistance, we evaluated endocrine function and measured Gs activity of erythrocyte membranes from AHO patients with clinical hormone resistance (PHP type Ia) and from family members with AHO alone (pseudopseudohypoparathyroidism). The results of erythrocyte membrane Gs determinations were compared to those of unaffected relatives and normal subjects. Patients with pseudopseudohypoparathyroidism (pseudoPHP) had reductions in erythrocyte membrane Gs activity comparable to those in patients with PHP type Ia [43.4 +/- 11.9% (+/- SD) for PHP type Ia vs. 47.8 +/- 9.5% for pseudoPHP]. However, in contradistinction to patients with PHP type Ia, individuals with pseudoPHP did not have obvious endocrine dysfunction. Although deficient Gs activity appears to play an important role in the pathogenesis of these disorders, it is possible that Gs deficiency must be combined with other factors that limit cAMP production to cause clinically overt endocrine disease.

The inhibitory adenylate cyclase coupling protein in pseudohypoparathyroidism

Deficient activity of the adenylate cyclase stimulatory coupling protein (Ns) has been demonstrated in many patients with pseudohypoparathyroidism type I (PHP) who have Albright's hereditary osteodystrophy and multiple hormone resistance. Since an abnormality in the activity of the related adenylate cyclase inhibitory coupling protein (Ni) could influence hormone responsiveness, we measured pertussis toxin-catalyzed [32P]ADP ribosylation of the 40,000-dalton alpha-subunit of Ni (Ni alpha) in erythrocyte membranes from patients with PHP and normal subjects. There were no significant differences in the amounts of Ni alpha in membranes from normal subjects, patients with PHP who have low Ns associated with Albright's hereditary osteodystrophy and multiple hormone resistance, and patients with PHP who have normal Ns. Abnormal Ni is not likely to cause hormone resistance in patients with PHP who have normal Ns or to influence hormone responsiveness in patients with PHP who have low Ns.

Vitamin D-dependent rickets type II. Defective induction of 25-hydroxyvitamin D3-24-hydroxylase by 1,25-dihydroxyvitamin D3 in cultured skin fibroblasts

1,25(OH)2D3 induces 25(OH)D3-24-hydroxylase (24-OHase) in cultured skin fibroblasts from normal subjects. We evaluated 24-OHase induction by 1,25(OH)2D3 in skin fibroblasts from 10 normal subjects and from four unrelated patients with hereditary resistance to 1,25(OH)2D or vitamin D-dependent rickets type II (DD II). Fibroblasts were preincubated with varying concentrations of 1,25(OH)2D3 for 15 h and were then incubated with 0.5 microM [3H]25(OH)D3 at 37 degrees C for 30 min; lipid extracts of the cells were analyzed for [3H]24,25(OH)2D3 by high performance liquid chromatography and periodate oxidation. Apparent maximal [3H]24,25(OH)2D3 production in normal cell lines was 9 pmol/10(6) cells per 30 min and occurred after induction with 10(-8) M 1,25(OH)2D3. 24-OHase induction was detectable in normal fibroblasts at approximately 3 X 10(-10) M 1,25(OH)2D3. [3H]24,25(OH)2D3 formation after exposure to 1,25(OH)2D3 was abnormal in fibroblasts from all four patients with DD II. In fibroblasts from two patients with DD II, [3H]24,25(OH)2D3 formation was unmeasurable (below 0.2 pmol/10(6) cells per 30 min) at 1,25(OH)2D3 concentrations up to 10(-6) M. Fibroblasts from the other two patients with DD II required far higher than normal concentrations of 1,25(OH)2D3 for detectable [3H]24,25(OH)2D3 induction. In one, [3H]24,25(OH)2D3 production reached 2.9 pmol/10(6) cells per 30 min at 10(-6) M 1,25(OH)2D3 (30% normal maximum at 10(-6) M 1,25(OH)2D3). In the other, [3H]24,25(OH)2D3 production achieved normal levels, 7.3 pmol/10(6) cells per 30 min after 10(-6) M 1,25(OH)2D3. The two patients whose cells had a detectable 24-OHase induction by 1,25(OH)2D3 showed a calcemic response to high doses of calciferols in vivo. Our current observations correlate with these two patients' responsiveness to calciferols in vivo and suggest that their target organ defects can be partially or completely overcome with extremely high concentrations of 1,25(OH)2D3. The two patients whose cells showed no detectable 24-OHase induction in vitro failed to show a calcemic response to high doses of calciferols in vivo.

IN CONCLUSION

(a) the measurement of 24-OHase induction by 1,25(OH)2D3 in cultured skin fibroblasts is a sensitive in vitro test for defective genes in the 1,25(OH)2D effector pathway. (b) This assay provides a useful tool for characterizing the target tissue defects in DD II and predicting response to calciferol therapy.

Impaired formation of beta-adrenergic receptor-nucleotide regulatory protein complexes in pseudohypoparathyroidism

Decreased activity of the guanine nucleotide regulatory protein (N) of the adenylate cyclase system is present in cell membranes of some patients with pseudohypoparathyrodism (PHP-Ia) whereas others have normal activity of N (PHP-Ib). Low N activity in PHP-Ia results in a decrease in hormone (H)-stimulatable adenylate cyclase in various tissues, which might be due to decreased ability to form an agonist-specific high affinity complex composed of H, receptor (R), and N. To test this hypothesis, we compared beta-adrenergic agonist-specific binding properties in erythrocyte membranes from five patients with PHP-Ia (N = 45% of control), five patients with PHP-Ib (N = 97%), and five control subjects. Competition curves that were generated by increasing concentrations of the beta-agonist isoproterenol competing with [125I]pindolol were shallow (slope factors less than 1) and were computer fit to a two-state model with corresponding high and low affinity for the agonist. The agonist competition curves from the PHP-Ia patients were shifted significantly (P less than 0.02) to the right as a result of a significant (P less than 0.01) decrease in the percent of beta-adrenergic receptors in the high affinity state from 64 +/- 22% in PHP-Ib and 56 +/- 5% in controls to 10 +/- 8% in PHP-Ia. The agonist competition curves were computer fit to a "ternary complex" model for the two-step reaction: H + R + N in equilibrium HR + N in equilibrium HRN. The modeling was consistent with a 60% decrease in the functional concentration of N, and was in good agreement with the biochemically determined decrease in erythrocyte N protein activity. These in vitro findings in erythrocytes taken together with the recent observations that in vivo isoproterenol-stimulated adenylate cyclase activity is decreased in patients with PHP (Carlson, H. E., and A. S. Brickman, 1983, J. Clin. Endocrinol. Metab. 56:1323-1326) are consistent with the notion that N is a bifunctional protein interacting with both R and the adenylate cyclase. It may be that in patients with PHP-Ia a single molecular and genetic defect accounts for both decreased HRN formation and decreased adenylate cyclase activity, whereas in PHP-Ib the biochemical lesion(s) appear not to affect HRN complex formation.

Persistent hyperparathyroidism caused by incomplete parathyroid resection and a hyperfunctioning parathyroid autograft

A case of familial primary hyperparathyroidism occurred in which persistent hypercalcemia was caused by hyperplastic parathyroid tissue left in the neck and mediastinum after initial surgery and by a hyperfunctioning parathyroid autograft in the forearm. Successful therapy required parathyroid localization and resection of tissue from the neck, mediastinum, and forearm. Parathyroid tissue should be autotransplanted at the time of initial surgery only when total parathyroidectomy is judged likely to have been achieved.

Urinary calcium excretion in familial hypocalciuric hypercalcemia. Persistence of relative hypocalciuria after induction of hypoparathyroidism

Familial hypocalciuric hypercalcemia (FHH) is an autosomal dominant trait comprising hypercalcemia, hypophosphatemia, parathyroid hyperplasia, and unusually low renal clearance of calcium. We evaluated the role of parathyroid hormone in the relative hypocalciuria of FHH and characterized the renal transport of calcium in this disorder using three previously hypercalcemic FHH patients with surgical hypoparathyroidism and three controls with surgical hypoparathyroidism. Intravenous infusion of calcium chloride in two patients with FHH and in three controls increased serum calcium from a mean basal of 5.0 to a mean peak of 6.8 meq/liter in two FHH patients and from 4.2 to 5.7 in three control subjects. Urinary calcium in a third FHH patient was studied without calcium infusion during recovery from hypercalcemia of vitamin D intoxication. At all serum concentrations of calcium, calcium clearance was lower in FHH than in controls; at base-line serum calcium, the ratio of calcium clearance to inulin clearance (C(Ca)/C(IN)) in FHH subjects was 32% of that in controls and decreased to 19% during hypercalcemia. Calcium infusion increased the ratio of sodium clearance to inulin clearance in controls from a base line of 0.020 to 0.053 at peak concentrations of calcium in serum, but did not affect this parameter in FHH (0.017 at base-line serum calcium vs. 0.019 at peak). When calcium infusion studies were performed (in two patients with FHH and one control) during administration of acetazolamide, a drug whose principal renal action causes inhibition of proximal transport of solute, C(Ca)/C(IN) in the patients with FHH was 29 and 7% of that of the control at base-line and peak serum calcium, respectively. In contrast, ethacrynic acid, a diuretic that acts in the ascending limb of the loop of Henle, increased C(Ca)/C(IN) more in the FHH patients than in the control subject; C(Ca)/C(IN) was 65% at base-line and 47% at peak serum calcium, compared with that of the control subject. The greater calciuric response to ethacrynic acid than to acetazolamide or calcium infusion alone in FHH indicates that a major renal locus of abnormal calcium transport in this disorder may be the ascending limb of the loop of Henle.Decreased clearance of calcium in patients with FHH and hypoparathyroidism when compared with hypoparathyroid controls indicates that relative hypocalciuria in FHH is not dependent on hyperparathyroidism. Since the parathyroid glands in FHH are not appropriately suppressed by calcium, this implies that FHH represents a disorder of abnormal transport of, and/or response to, extracellular calcium in at least two organs, parathyroid gland and kidney.

Deficient guanine nucleotide regulatory unit activity in cultured fibroblast membranes from patients with pseudohypoparathyroidism type I. a cause of impaired synthesis of 3',5'-cyclic AMP by intact and broken cells

Deficient activity of the guanine nucleotide regulatory protein (G unit), an integral component of the membrane-bound adenylate cyclase complex, has been implicated as the biochemical lesion in many patients with pseudohypoparathyroidism (PHP) type I. In addition to renal resistance to parathyroid hormone in this disorder, there is decreased responsiveness of diverse tissues to hormones that act via 3',5'-cyclic AMP (cAMP). To assess whether a deficiency of G units could account for impaired adenylate cyclase activity, we studied cAMP production in intact cultured fibroblasts and fibroblast plasma membranes from five patients with PHP in response to several activators of adenylate cyclase. The number of G units in PHP fibroblast membranes, measured by cholera toxin-dependent [(32)P]ADP ribosylation of G-unit peptides, as well as the G-unit activity, determined by the ability of detergent extracts to reconstitute adenylate cyclase activity in G-unit-deficient S49 CYC(-) membranes, were found to be markedly reduced compared with control membranes (43 and 40%, respectively), The activation of fibroblast membrane adenylate cyclase by effectors that act directly through the G unit (guanosine triphosphate, guanosine 5'-0-[3-thiotriphosphate] [GTP-gamma-S], NaF) was significantly greater in control membranes than in membranes from patients with PHP. Moreover, we found that hormone (prostaglandin E(1)) stimulated adenylate cyclase activity was also greater in control membranes than in PHP membranes. Neither the apparent affinity of membrane adenylate cyclase for GTP-gamma-S (apparent K(m) =5 X 10(-8) M) nor the rate of enzyme activation by GTP-gamma-S was significantly different in fibroblast membranes from control subjects and patients with PHP. In contrast to the notable differences in hormone and G-unit-activated adenylate cyclase shown in fibroblast membranes from PHP patients and control subjects, the intrinsic catalytic activity of membranes, as determined by forskolin-stimulated adenylate cyclase, was not significantly different in the two groups. Intact fibroblasts derived from patients with PHP accumulated significantly (P 0.001) less cAMP (46+/-21 pmol cAMP/mcg DNA, n = 5) than cells from normal individuals (170+/-51 pmol cAMP/mcg DNA, n = 11) when stimulated with PGE(1). PGE(1)-stimulated accumulation of cAMP by intact fibroblast monolayers correlated closely with PGE(1) plus GTP-activated membrane adenylate cyclase activity in both patients and controls (r = 0.97, P < 0.001). Our data show that, in patients with PHP, (a) fibroblast membranes show a decreased complement of G units, (b) membrane catalytic activity is normal, but adenylate cyclase activity is reduced when stimulated by hormone or by effectors which activate the G unit, (c) the ability of cells to accumulate cAMP in response to hormone stimulation is reduced, and (d) reduced membrane adenylate cyclase activity correlates well with impaired cellular cAMP synthesis. These results, taken together, indicate that a deficiency of G-unit activity can impair synthesis of cAMP by both intact and broken cells, and may explain the resistance of multiple tissues to hormones that act via cAMP observed in PHP.

Work in progress: abnormal parathyroid glands. Comparison of nonselective arterial digital arteriography, selective parathyroid arteriography, and venous digital arteriography as methods of detection

Nonselective arterial digital arteriography (NSADA), selective parathyroid arteriography (SPA), and venous digital arteriography (VDA) were compared as methods of detecting parathyroid enlargement in 14 patients with primary hyperparathyroidism undergoing preoperative localization following unsuccessful neck surgery. All 14 had SPA and NSADA, consisting of contrast injections into the ascending aorta, innominate artery, and left subclavian artery; 7 also had VDA. Surgery was performed in 9 patients, and 2 additional glands were confirmed by fine-needle aspiration and venous sampling. Parathyroid glands could not be located in 3 patients, who were not re-explored. SPA demonstrated 11/13 abnormal glands (85%). NSADA detected 7/13 (54%), and there were 2 false positives. VDA showed 5/6 glands detected by NSADA (83%); the seventh patient did not have VDA. The overall quality of VDA was inferior to NSADA. Although NSADA and VDA are less sensitive than SPA, they are safer and easier to perform and should be the initial vascular screening procedures following unsuccessful parathyroid surgery.

Aspiration of enlarged parathyroid glands for parathyroid hormone assay

Enlarged parathyroid glands were percutaneously aspirated under computed tomographic (CT) control in 7 patients, and levels of parathyroid hormone (PTH) and human thyroglobulin (HTg) were measured. All 7 patients had high levels of PTH in at least 1 specimen. It is concluded that the measurement of high concentrations of PTH in the aspirate from a cervical or mediastinal mass, with CT documentation of needle position, provides absolute localization of parathyroid masses.

Deficient adenylate cyclase regulatory protein in renal membranes from a patient with pseudohypoparathyroidism

Recent studies have established that some patients with pseudohypoparathyroidism have a deficiency of the adenylate cyclase regulatory protein (the G unit) in plasma membranes from erythrocytes, platelets, and fibroblasts. We have directly measured the activity of the G unit in renal membranes from a patient with pseudohypoparathyroidism who, in addition to parathyroid hormone resistance, has resistance to thyrotropin and gonadotropins. Erythrocyte membrane G unit activity was 57% that of control erythrocyte membranes. Lubrol PX extracts of renal membranes had only 30% of the G unit activity of control renal membrane extracts, whether assayed with sodium fluoride or guanosine-5'-O-(3-thiotriphosphate) (GTP-gamma-S). In cholate extracts, the G unit activity was 37 and 48% of control with fluoride or GTP-gamma-S, respectively. Cholera toxin-dependent incorporation of [32P]ADP-ribose into the 42,000-Mr subunit of the G unit was decreased in renal membranes from the patient compared with control renal membranes. The data demonstrate that the membrane G unit deficiency in pseudohypoparathyroidism extends to the cells of a clinically relevant parathyroid hormone target tissue.

Deficiency of hormone receptor-adenylate cyclase coupling protein: basis for hormone resistance in pseudohypoparathyroidism

Pseudohypoparathyroidism is an inherited disorder associated with resistance to the action of several hormones, including parathyroid hormone, thyroid-stimulating hormone, follicle-stimulating hormone, and luteinizing hormone. The disorders described under this designation are heterogeneous in regard to the underlying genetic defects, the phenotypic manifestation, and the severity of the defects in hormone action. The majority of affected individuals who also have the characteristic skeletal changes (heredity osteodystrophy) have a defect in the guanine nucleotide regulatory protein (G protein) that is essential for coupling certain cell-surface hormone receptors to the adenylate cyclase system. This defect is probably the cause for resistance to the action of multiple hormones. In the remaining patients the cause for hormone resistance has not been identified.

Vanadate stimulates adenylate cyclase via the guanine nucleotide regulatory protein by a mechanism differing from that of fluoride

Vanadate stimulates adenylate cyclase activity in turkey erythrocyte membranes. The maximal stimulation is 7-fold over basal at 3 mM vanadate; higher concentrations are inhibitory. A suboptimal concentration of fluoride (1 mM) together with vanadate (3 mM) activates adenylate cyclase in a non-additive manner; cyclase activation by optimal fluoride (10 mM) is inhibited by vanadate (3 mM). There is no stimulation by vanadate of adenylate cyclase activity (measured either with Mg2+ or Mn2+) in CYC- S49 lymphoma cell membranes. Vanadate (3 mM) shows no effect on binding of Beta-adrenergic agonists or antagonists to the [3H] (-)-dihydroalprenolol binding site in turkey erythrocyte membranes. These results suggest that the effect of vanadate on Adenylate cyclase is mediated through the nucleotide regulatory protein and may act by a mechanism similar to fluoride. However, in cholera toxic-treated membranes as well as in GDP-beta-S plus isoproterenol-treated membranes, fluoride-stimulated adenylate cyclase activity is significantly reduced, but vanadate stimulation is not. Our results suggest that although the actions of vanadate and fluoride in adenylate cyclase may each involve the nucleotide regulatory unit, the exact mechanisms of activation by the two anions differ.

Parathyroid imaging after intraarterial injections of [75Se]selenomethionine

Thirteen patients with persistent hyperparathyroidism after unsuccessful neck surgery were given up to 250 microCi [75Se]selenomethionine intraarterially during parathyroid arteriography, gamma-Camera images of the neck and mediastinum localized abnormal parathyroids in four of five patients receiving complete injections, despite very small glands or unsuccessful arteriograms in some of the patients. Correctly localizing images were obtained in three patients receiving incomplete injections. However, images in five of eight of the remaining patients receiving incomplete injections showed areas of false positive uptake, and there was no way preoperatively to distinguish these from the true positive studies. We conclude that intraarterial injection of radioselenomethionine is a simple supplementary procedure in patients undergoing arteriography that may, with proper technique, be useful in identifying small foci of abnormal parathyroid tissue.

Restoration of guanine nucleotide- and fluoride-stimulated activity to an adenylate cyclase-deficient cell line with affinity-purified guanine nucleotide regulatory protein

A guanine nucleotide-binding protein purified from turkey erythrocytes by affinity chromatography confers both F-- and guanine nucleotide-stimulation of adenylate cyclase to membranes from CYC- cells, a mutant cell line deficient in these responses. Interaction of turkey erythrocyte membranes with beta-adrenergic agonists before affinity chromatography, which is essential for binding of the guanine nucleotide regulatory protein to the affinity matrix, was also required for recovery of F--stimulation restoring activity in the affinity eluate.

Adenosine 3',5'-monophosphate response to parathyroid hormone: familial hypocalciuric hypercalcemia versus typical primary hyperparathyroidism

We investigated cAMP metabolism during and after a 15-min infusion of parathyroid hormone (PTH) in 7 normals, 13 patients with typical primary hyperparathyroidism (1HPT), and 6 patients with familial hypocalciuric hypercalcemia (FHH). Nephrogenous urinary cAMP excretion rate reached a peak during the first or second 30 min urine collection interval after the start of the PTH infusion in all subjects. cAMP concentration in plasma reached a peak within 5--20 min of the start of the infusion and then decreased with an initial half-time of 15 min. The peak value of nephrogenous urinary cAMP excretion rate was lower in the group with 1HPT than in the group with FHH or in normals (119 vs, 275 vs. 204 nmol/100 ml glomerular filtrate; P less than 0.0 5 for both comparisons). Similarly, the peak value of plasma cAMP concentration was less in 1HPT subjects than in FHH patients or in normals (11.1 vs. 17.1 vs. 16.6 nmol/100 ml, respectively; P less than 0.05 for both comparisons). For purposes of diagnostic classification, the two hypercalcemia groups could be more completely separated by the values of either the renal calcium to creatinine clearance ratio or the plasma PTH concentration than by the values of inidices of cAMP response to PTH. The differences in cAMP response to PTH between FHH and 1HPT patients could be secondary to differences in circulating PTH concentrations (these are lower in subjects with FHH) or could reflect a renal lesion more closely related to the underlying etiology of FHH.

Familial hypocalciuric hypercalcemia: recognition among patients referred after unsuccessful parathyroid exploration

Of 67 patients referred after unsuccessful surgery for presumed primary hyperparathyroidism, six were shown to be members of kindreds with familial hypocalciuric hypercalcemia. This diagnosis had not been recognized in any of the six previosuly. Most of the remaining 61 cases had proven or probable typical primary hyperparathyroidism, and a subgroup of four had hypercalcemia with suppression of the parathyroid glands. Urine calcium excretion expressed as the calcium:creatinine clearance ratio provided an easily measurable and effective index to separate the groups with familial hypocalciuric hypercalcemia, typical primary hyperparathyroidism, and suppressed parathyroids. Thus, at least 9% of patients referred after unsuccessful parathyroidectomy had familial hypocalciuric hypercalcemia. The assessment of urine calcium excretion by indices such as the calcium:creatinine clearance ratio should facilitate recognition of this condition, which responds poorly to standard subtotal parathyroidectomy.

A familial syndrome of decrease in sensitivity to 1,25-dihydroxyvitamin D

Typical features of hereditary vitamin D-dependent (pseudovitamin D-deficient) rickets were observed beginning at ages 20 and 5 months in a brother and sister. Both had calcium malabsorption correctable with high doses of 25-hydroxyvitamin D. During periods of hypocalcemia they both manifested secondary hyperparathyroidism with hypophosphatemia and high serum concentrations of endogenously produced 1,25-dihydroxyvitamin D. In each, normalization of serum calcium concentration and resolution of osteomalacia were obtained with continuous administration of high doses of ergocalciferol or high doses of 1,25-dihydroxycholecalciferol. Chemical features of vitamin D deficiency were corrected in the presence of high circulating concentrations of 1,25-dihydroxyvitamin D2, produced endogenously, or of 1,25-dihydroxyvitamin D3, administered by mouth. Serum concentrations of 25-hydroxyvitamin D2, 25-hydroxyvitamin D3, 24,25-dihydroxyvitamin D, and 1,25-dihydroxyvitamin D were normal in five first degree relatives. We conclude that in these five first degree relatives. We conclude that in these siblings, rickets and osteomalacia resulted from a hereditary decreased sensitivity to 1,25-dihydroxyvitamin D at the intestine and perhaps other vitamin D target tissues.