Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0221002 (primary hyperparathyroidism)
 4,921 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The authors report on various diagnostic pitfalls on 102 patients having undergone exploratory cervicotomy for primary hyperparathyroidism. A false positive diagnostic error was made on 2% of the cases, bringing to 100 the number of patients with a confirmed diagnosis of primary hyperparathyroidism. False negative diagnosis was made on 4% of the patients: two late diagnoses leading to an acute toxic state and death postoperatively in both cases; two pure psychiatric variants leading to repetitive hospitalizations in psychiatry. Error in diagnosis because of a masking effect was made in 4% of the cases:--one association with a clear cell nephro--epithelioma--one association with a multiple myeloma--two associations with a benign monoclonal gammapathy. The absence of hypercalcemia, a diagnostic pitfall in the modern form of this disease was found in 7% of the cases. PTH hypersecretion which is virtually a constant finding in the normocalcemic form of the disease obviates in most cases the need of a bone biopsy and quantitative histomorphometric analysis. The association with another endocrinopathy was found in 12% of the cases (2 MEN I, 1 MEN II, 9 hyperthyroidism). Because of its high frequency in the aged (22% greater than 75 years) the diagnosis of this disease is difficult for its signs are mimicked as well by the aging process. The preoperative topographic diagnostic error is avoided since there doesn't seem to be any test which would preclude the normal surgical procedure of carefully exploring all 4 topographic sites of the parathyroid. Surgical errors can be numerous but minimized with the increasing experience of the operator. Histological errors are seen mainly in the normocalcemic variety where only electron microscopy can detect the typical signs of cellular hyperactivity.
 ...
PMID:[Primary hyperparathyroidism. Apropos of 102 recent exploratory cervicotomies: diagnostic and clinical pitfalls]. 264 28

The parathyroid gland possesses receptors for 1,25-dihydroxyvitamin D3, the active metabolite of the vitamin D system, and in vitro experiments have shown that 1,25-dihydroxyvitamin D3 can inhibit the secretion of PTH. In this study 31 subjects who had displayed persistent mild hypercalcemia for 14 years and presumably had mild primary hyperparathyroidism (HPT) were challenged with 1.0 microgram alphacalcidol (1 alpha-(OH)-vitamin D3) over 6 months in a double-blind, placebo-controlled study. Before initiation of therapy, the hyperparathyroid subjects showed lower serum levels of 1,25-dihydroxyvitamin D in relation to PTH or calcium when compared with age- and sex-matched controls. Treatment induced a slight rise in serum calcium (0.05 mmol/l), but no significant decrease of the PTH levels. Eighteen of the subjects thereafter entered an open study with a higher dose of alphacalcidol (2.0 micrograms) over 1 year. Although this high dose induced a marked rise in serum calcium (0.17 mmol/l), there was only a transient reduction of the PTH levels. Thus, during long-term condition there was an escape from the suppressive action of the elevated calcium concentrations and no evidence of a specific inhibition of PTH secretion by a small oral dose of active vitamin D.
 ...
PMID:Treatment with active vitamin D (alphacalcidol) in patients with mild primary hyperparathyroidism. 264 46

Interpretation of serum immunoreactive PTH measurements requires an understanding of the secretion, metabolism, and heterogeneity of circulating immunoreactive PTH. Both intact hormone and biologically inactive carboxyl fragments containing the middle and C-terminal regions are secreted by the parathyroid glands. Inactive fragments also are produced peripherally by metabolism of intact hormone by liver and kidney. Inactive fragments represent 75 to 95% of the total immunoreactivity in serum, a consequence of their long half-life in vivo as compared with intact hormone. Immunoassays for PTH can be divided into those measuring intact hormone (N-terminal, intact) and those measuring both inactive fragments and intact hormone (mid-region, C-terminal, polyvalent). The latter principally measures inactive fragments because of their greater concentration as compared with intact hormone in peripheral serum. The clinical utility of PTH assays varies considerably because of differences in their specificity and sensitivity. Serum PTH levels have been more often observed to be elevated in individuals with primary hyperparathyroidism with the use of research quality radioimmunoassays that recognize both inactive fragments and intact hormone than with conventional N-terminal or intact assays. Homologous mid-region assays have provided exceptional clinical sensitivity in confirming primary hyperparathyroidism. Comparison of a sensitive mid-region radioimmunoassay with a recently developed two-site, noncompetitive chemiluminescent immunoassay for intact PTH indicated that both methods were highly useful in the differential diagnosis of hypercalcemia. The mid-region assay provided the best diagnostic sensitivity in primary hyperparathyroidism with more elevated levels of PTH. The sensitivity of the intact assay was good, a significant improvement over conventional N-terminal and intact assays. The specificity of the intact assay was clearly superior, with measured PTH levels found to be suppressed to below normal in most subjects with hypercalcemia associated with malignancy. In contrast, measured levels were primarily normal with the mid-region assay. The higher levels of immunoreactive PTH observed in nonparathyroid hypercalcemia with the mid-region assay are in agreement with the measurement of biologically inactive carboxyl fragments, which continue to be secreted in hypercalcemia.
 ...
PMID:Measurement of parathyroid hormone. 267 65

Primary hyperparathyroidism is a common disorder and one that can usually (approximately 95%) be successfully treated by parathyroidectomy. PTH assays have become quite accurate for confirming the diagnosis. In patients with malignancy-associated hypercalcemia, parathyroid-like protein levels are usually increased, and radioimmunoassays being developed to quantitate serum levels of this protein will make the diagnosis easier. Treatment for a parathyroid adenoma is removal of the tumor and identification of the normal parathyroid glands. Treatment for primary or secondary hyperplasia is usually subtotal parathyroidectomy. Recurrent hyperparathyroidism is uncommon, except in patients with familial hyperparathyroidism, MEN-1 parathyroid carcinoma, or renal failure and secondary hyperparathyroidism. Persistent hyperparathyroidism is more common and is usually due to surgeon inexperience, but it is also caused by ectopically situated parathyroid glands, multiple abnormal parathyroid glands, or supranumerary parathyroid glands. Preoperative localization studies using ultrasound, thallium-technetium scanning, MRI, or CT scanning are reliable in patients with solitary parathyroid adenomas, but often fail to detect all of the abnormal parathyroid tissue in patients with multiple abnormal parathyroid glands. Intraoperative use of urinary cyclic AMP assays and rapid PTH assays have recently been used experimentally during parathyroid explorations to determine whether all hyperfunctioning parathyroid tissue has been removed, but these methods are not yet reliable or fast enough to be generally accepted. Most patients with primary hyperparathyroidism who are successfully treated by parathyroidectomy experience psychological, clinical, and metabolic benefits.
 ...
PMID:Primary hyperparathyroidism. A surgical perspective. 267 68

Familial benign hypercalcemia, or hypocalciuric hypercalcemia, may be defined as a dominantly inherited disorder of calcium and magnesium metabolism, characterized by lifelong hypercalcemia and hypermagnesemia (both of variable degree), that usually is not associated with any symptoms, physical signs, reduced vitality, or ill health. Chondrocalcinosis, pancreatitis, gallstones, and neonatal primary hyperparathyroidism are possible rare associations, but findings differ among various studies. The biochemical findings are bland, with "normal" values for serum PTH by many techniques, modest hypophosphatemia, and other findings usually normal. A low calcium:creatinine clearance ratio is suggestive of, but not diagnostic for, FBH; urinary calcium excretion less than 100 mg per day may be just as helpful. The diagnosis should not be made casually or without family screening, because the findings in a given patient may be identical to those in mild primary hyperparathyroidism. The major rationale for careful evaluation is to diagnose the syndrome of FBH and to help affected family members avoid needless expense and the risk of further evaluation and treatment.
 ...
PMID:Familial benign (hypocalciuric) hypercalcemia. A troublesome mimic of mild primary hyperparathyroidism. 267 70

Hypercalcaemia is a frequent situation in clinical practice. An earlier detection is facilitated by routine analysis of serum calcium. The clinical manifestations depend on severity and the rate of onset of hypercalcaemia. Paucisymptomatic and asymptomatic presentations are the most frequent. Causes of hypercalcaemia are numerous and the mechanisms are various. PTH and vit. D play a preponderant part. In first of all iatrogenic cause are eliminated (all vit D preparations, thiazide diuretics, milk-alkali syndrome). Among non neoplastic hypercalcaemia primary hyperparathyroidism is the first diagnosis. Nephrolithiasis and asymptomatic forms are the most frequent presentations actually. The biochemical profile is not always typical. Generally the association of echography and tomodensitometry lead to the topographic diagnosis. Parathyroid surgical exploration is often necessary in difficult cases. Secondary, the other rare causes of hypercalcaemia are studied: sarcoidosis and granulomatosis disease, thyrotoxicosis and dome endocrinopathies, immobilisation hypercalcaemia, familial hypocalciuric, hypercalcaemia. All of this causes of hypercalcaemia are potentially reversible.
 ...
PMID:[Non-neoplastic hypercalcemia]. 271 64

The mechanisms of hypercalcemia were assessed in 15 patients with humoral hypercalcemia of malignancy (HHM) who had tumors at various stages of progression. In patients with early tumors, bone biopsies were generally normal and the hypercalcemia was due to an elevation in renal tubular resorption of calcium. Conversely, osteoclastic resorption was markedly increased in patients with advanced tumors, particularly those in whom the biopsies were obtained postmortem. Osteoclast surface (Oc.S) correlated positively with the stage of tumor progression (r = 0.80, p less than 0.002), degree of immobility (r = 0.87, p less than 0.002), and level of urinary cyclic AMP excretion (r = 0.60, p less than 0.02). When compared with a group of ambulant patients with primary hyperparathyroidism (HPT), osteoblast surface (Ob.S%) in HHM was depressed (median and range): 1.2% (0-11.6%) versus 5.3% (1.1-32.0%) (p less than 0.001). However, a relatively low Ob.S (4%) and raised Oc.S (43.5%) were also seen in an immobilized patient with severe HPT. These data suggest that the PTH-related peptides currently invoked in the pathogenesis of HHM may initially cause hypercalcemia by enhancing renal tubular calcium resorption. The increase in osteoclastic activity and depression of osteoblastic activity that subsequently occurs is probably due to the combined effects of immobilization and higher circulating levels of PTHrP on the skeleton. However, the release of other bone-resorbing factors by the tumor, which have a depressant effect on osteoblastic activity, remains possible.
 ...
PMID:Contrasting mechanisms of hypercalcemia in patients with early and advanced humoral hypercalcemia of malignancy. 271 73

Serum levels of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), 25-hydroxyvitamin D3 (25(OH)D3), C-terminal immunoreactive PTH (iPTH), calcium and phosphate, and endogenous creatinine clearance (Clcr) were measured in 34 patients with primary hyperparathyroidism. Clcr ranged from 13 to 161 ml/min (mean 72). S-iPTH was elevated in 82% of the patients and correlated positively to serum calcium (r = 0.74, P less than 0.001) and inversely to Clcr (r = -0.50, P less than 0.02). S-25(OH)D3 was reduced in 28% of the patients and depended on regular multivitamin supplementation (P less than 0.005). S-1,25(OH)2D3 was increased in 26% of the patients and decreased in 9%. It was positively correlated to S-25(OH)D3 (r = 0.39, P less than 0.05) and Clcr (r = 0.42, P less than 0.02) and inversely to serum levels of calcium (r = -0.39, P less than 0.05), phosphate (r = -0.42, P less than 0.02) and iPTH (r = -0.40, P less than 0.05). Multiple regression analysis revealed a positive correlation to 25(OH)D3 when Clcr was taken into account and to Clcr when S-25(OH)D3 was taken into account. When both variables were considered no significant partial correlations were found between S-1,25(OH)2D3 and serum calcium, phosphate and PTH, respectively. It is concluded that serum levels of 25(OH)D3 and renal function are the main determinants for S-1,25(OH)2D3 in primary hyperparathyroidism.
 ...
PMID:Determinants for serum 1,25-dihydroxycholecalciferol in primary hyperparathyroidism. 272 Jan 98

Two antisera, C-52 and C-97, raised against bovine (b)PTH(1-84) in guinea pigs, were evaluated with 125I-[tyr53] human (h)PTH(53-84) as tracer and intact hPTH(1-84) and synthetic hPTH(39-84), representative of large carboxylterminal ("C") fragments found in circulation, as standards. In both assays, hPTH(39-84) was 5-6 times more potent than hPTH(1-84) on a molar basis in displacing the tracer. With both antisera, progressive deletion at the aminoterminal end of large "C" fragments, as in hPTH(53-84) and hPTH(65-84), lead to decreased immunoreactivity, hPTH(69-84) being non-immunoreactive. The mid-carboxylterminal fragments, hPTH(44-68) and hPTH(39-68), did not react in either assay. Each antiserum measured known quantities of pure hPTH(1-84) or hPTH(39-84) standards similarly. Serum PTH values obtained with antiserum C-97 were about 3 times higher in renal failure, 1.75 times higher in normal individuals and those with primary hyperparathyroidism, while similar to values measured with antiserum C-52 in individuals with secondary hyperparathyroidism without renal failure or with pseudohypoparathyroidism. When circulating PTH taken from patients with these disorders was fractionated by gel chromatography, both antisera recognized similar peaks of intact hPTH(1-84) and of large "C" fragments while antiserum C-97 further recognized a peak of smaller "C" fragments. This explained the different clinical behavior of the latter antiserum. Our findings demonstrate the existence of small late "C" fragments in circulation. They further suggest an influence of serum calcium and of renal function on the quantity of these fragments.
 ...
PMID:Immunological evidences for the presence of small late carboxylterminal fragment(s) of human parathyroid hormone (PTH) in circulation in man. 274 18

Primary hyperparathyroidism (PH) is now considered a common condition. Its frequency and the deleterious long-term effects of hypercalcemia make a correct diagnosis mandatory. We attempted to evaluate the usefulness of the indexes of parathyroid function and hormone measurements more commonly used in the diagnosis of PH. To this end we studied 64 patients, distributed in three groups: group with PH, group with hypercalciuric renal lithiasis (HRL) and control group (CG). The results were evaluated with a test of comparison of means and a stepwise discriminating regression analysis. The 8 most useful measurements to differentiate PH from HRL and CG were serum calcium, corrected serum calcium, serum phosphorus, fasting calcium excretion (FCE), maximal tubular calcium reabsorption (MTCR), maximal tubular phosphate reabsorption (MTPR), osteocalcin, PTH half molecule (PTH-HM) and 1,25-dihydroxyvitamin D. The 3-variable and 4-variable groups with a highest discriminating ability were: serum calcium, FCE and PTH-HM, and serum calcium, FCE, PTH-HM and MTPR. We think that the measurement of these four variables is the most adequate strategy for the diagnosis of PH.
 ...
PMID:[Biochemical profile of primary hyperparathyroidism. Comparative study with hypercalciuric renal lithiasis]. 274 10


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>