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Query: UMLS:C0221002 (primary hyperparathyroidism)
 4,921 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An assessment of free and total calcium measurements was made in 691 patients with suspected hypercalcemia or disorders often associated with hypercalcemia. In 18.9% of the 1049 specimens analyzed from nine different patient groups, a different impression of hypercalcemia was obtained depending on whether the free or total calcium was considered. Analysis of the ratio of free to total calcium indicated that there are two main factors which influence the distribution of calcium in the serum of hypercalcemic patients: the concentrations of albumin and parathyroid hormone. A lowered albumin concentration accounted for the altered distribution of calcium in patients with malignancies and partially accounted for the altered distribution in patients postrenal transplantation. In patients with confirmed primary hyperparathyroidism a higher ratio of free to total calcium was found, which could not be explained by alterations in protein, albumin, pH, or CO2 content but was related to parathyroid hormone concentration. Free calcium appears to be a slightly better indicator of elevated calcium states than total calcium. Measurements of free calcium should be particularly useful in patients with altered albumin concentration, with multiple myeloma in whom a calcium-binding protein could be present, after renal transplantation, and with suspected hyperparathyroidism and normal or slightly elevated total calcium values.
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PMID:Relationship of free and total calcium in hypercalcemic conditions. 42 92

Serum total calcium was measured in 1693 patients during a four-month period. We examined the effects of adjustment for albumin concentration on the interpretation of single measurements of serum total calcium and on the variation of series of measurements in individual patients. Markedly abnormal total calcium concentrations--2.75 mmol/l (11.0 mg/100 ml) or more, or 2.00 mmol/l (8.0 mg/100 ml) or less--were found in 115 patients, but only 24 (21%) remained markedly abnormal after adjustment for albumin. Three patients, two with malignant disease and one with primary hyperparathyroidism, had significant hypercalcaemia which was masked by hypoalbuminaemia. The serum total calcium measured on a subsequent occasion had changed 0.15 mmol/l (0.6 mg/100 ml) or more in 60 patients, but after adjustment for albumin this number was reduced to 27 (45%). The within-person standard deviation for serum total calcium was calculated in 26 patients with normal mean adjusted calcium concentrations who had had six or more sequential measurements. The mean standard deviation was 0.148 mmol/1 (0.59 mg/100 ml) and, after adjustment for albumin, this was reduced to 0.100 mmol/1 (0.40 mg/100 ml). We conclude that adjustment of serum total calcium concentration for albumin is essential to detect abnormal values and to assess changes in a value.
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PMID:Interpretation of serum total calcium: effects of adjustment for albumin concentration on frequency of abnormal values and on detection of change in the individual. 42 80

The prevalence of arterial hypertension in primary hyperparathyroidism (PHPT) is higher than in the general population. With the aim of determining the evolution of hypertension associated with PHPT, we analyzed a group of 56 patients followed for a mean of 60 months (range 10-101 months) after successful parathyroidectomy for PHPT. The study group consisted of 16 men and 40 women. The mean age was 49 +/- 12 years (range 18-73 years). None of the patients had renal impairment. Two hypertensive patients died during the follow-up from complications related to their hypertension. Twelve (21.8%) patients were hypertensive before parathyroid surgery (systolic greater than 160 mmHg and/or diastolic greater than 90 mmHg). Pre-operative midregion serum parathyroid hormone concentration was higher in the hypertensive patients than in normotensive patients (2.7 +/- 2.4 vs 0.82 +/- 0.4 mu iEq/l, p = 0.018). Pre-operative creatinine clearance was lower in the hypertensive patients than in normotensive patients (65.4 +/- 27.5 vs 86.7 +/- 26 ml/min, p = 0.002). There were no significant differences between normotensive and hypertensive patients in age, sex, body weight, clinical manifestations, weight of parathyroid tissue removed, and calcium metabolism, or in plasma concentrations of magnesium, uric acid, cholesterol, proteins, or albumin. During follow-up, none of the patients with pre-operative hypertension became normotensive, whereas 32% of the patients who were normotensive preoperatively developed clinical hypertension. The global prevalence of postoperative hypertension was thus 48%. The patients that developed hypertension after parathyroidectomy were followed for a longer period than the normotensive patients (76 +/- 17 vs 53 +/- 10 months, p = 0.005), had a lower postoperative creatinine clearance (74 +/- 28 vs 90 +/- 25 mg/min, p = 0.07), and higher cholesterol levels (6.2 +/- 1.5 vs 5.5 +/- 0.9 mmol/L, p = 0.08).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Long-term effects of parathyroidectomy for primary hyperparathyroidism on arterial hypertension. 141 42

In hospitalized patients primary hyperparathyroidism (HPT) and neoplasms account for more than 90% of all hypercalcemias. Measurements of parathyroid hormone, particularly when combined with dynamic tests using calcitonin and EDTA have a high specificity and sensitivity in the differential diagnosis of hypercalcemia but are time-consuming and costly for screening purposes. Most chemical autoanalyzers beside serum calcium also measure serum chloride, phosphate and albumin. In order to evaluate how these simple variables could differentiate between HPT and hypercalcemia due to malignant disorders, 110 measurements from HPT subjects and 111 measurements from cancer patients with hypercalcemia were used. Serum chloride was best among the simple variables to separate the two disorders and classified 84% of the hypercalcemic subjects correctly. When serum phosphatase and albumin were added giving the formula (serum chloride-84) x (albumin-15)/phosphate, only 3% of the cancer and 4% of the HPT subjects were misclassified when borderline values (400-500) were excluded (5% of the sample). In conclusion, while other more sensitive and expressive tests exist to establish the cause of hypercalcemia the above mentioned formula is a cheap and easy screening test for a preliminary diagnosis.
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PMID:Serum chloride in the differential diagnosis of hypercalcemia. 177 37

Recursive partitioning analysis was compared to logistic, linear and quadratic discriminant analyses in the ability to differentiate hypercalcemic patients with primary hyperparathyroidism from those with malignancy. Stepwise discriminant analysis identified serum albumin as the best single discriminant test. Albumin decision values optimally separating the two hypercalcemic groups were 39.46, 38.54, and 32.25 g/l for the logistic, linear and quadratic discriminant methods, respectively. Recursive partitioning analysis identified carboxy-terminus parathyroid hormone (PTH) as the best discriminant test with an optimal decision value of 8.2 mequiv/l. The discrepancy between the selection of PTH by recursive partitioning analysis and albumin by discriminant techniques was attributed to the nonnormal distribution of PTH. Recursive partitioning analysis using PTH classified 85.4% of the patients correctly. Logistic, linear and quadratic methods, using albumin as the predictor variable, correctly classified 79.6%, 78.6%, and 79.6% of patients, respectively.
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PMID:Comparison of nonparametric recursive partitioning to parametric discriminant analyses in laboratory differentiation of hypercalcemia. 181 62

Measurement of ionized calcium and cAMP in plasma and urine are used as sensitive parameters for the evaluation of calcium disorders. Ionized calcium is accepted as the biologically active form of calcium in the extracellular fluid, while urine cAMP provides an in vivo receptor assay for the biologically active parathyroid hormone. When urine is included as part of the calcium metabolic investigation it usually requires 24 h urine collection with a variety of different laboratory tests. Ionized calcium and cAMP are described in the literature in terms of several derived quantities, nomenclatures, and units which are rather unsystematic. The author developed reliable techniques and proposed systematic names and symbols and reference values for these quantities. Due to the lack of guidelines for the collection of urines in calcium metabolic evaluation, the author presented a simplified protocol (4 h standardized urine collection). In clinical investigation plasma and urine cAMP have been used to differentiate idiopathic hypoparathyroidism from pseudohypoparathyroidism (PsHP) based on the results of i.v. injection of parathyroid hormone (PTH). Nephrogenous cAMP has also been used for the detection of primary and secondary hyperparathyroidism with a high nosographic sensitivity (90%) (Broadus). The author showed that measurement of cAMP after i.v. PTH was a reliable and sensitive test to establish the diagnosis of PsHP, and that the urinary cAMP was useful for the diagnosis of secondary hyperparathyroidism in patients with jejunoileal bypass, but could not confirm the high nosographic sensitivity for the diagnosis of primary hyperparathyroidism. Further data are needed for proper conclusion. Although pursued vigorously the research into idiopathic stone formation using different protocols has not prevented stone recurrence nor indicated where further progress might be made. For the evaluation of recurrent calcium disease, the author proposed a simplified 4 h standardized urine collection with plasma albumin, urinary pH, standardized excretion rate of calcium, plasma phosphate glomerular filtration rate, and nephrogenous cAMP as the most important parameters. In this way the author obtained a sensitivity of 93% and specificity of 95.6% for the diagnosis of recurrent stone former. The test may therefore be of value for predicting the risk of recurrent stone formation in the single stone former.
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PMID:Ionized calcium and cyclic AMP in plasma and urine. Biochemical evaluation in calcium metabolic disease. 215 30

The measurement of serum intact parathyroid hormone (PTH) (1-84) over a 24-h period has shown the existence of a circadian rhythm in normal males which is absent in patients with primary hyperparathyroidism. The physiological significance of this observation is reflected in the presence of parallel changes in nephrogenous cyclic adenosine monophosphate (N-cAMP) in normals which are also absent in primary hyperparathyroidism. Serum calcium, adjusted for variations in albumin concentrations, showed a transient fall in normal subjects prior to the nocturnal rise in PTH (1-84). A similar transient fall in serum adjusted calcium was observed in the hyperparathyroid patients. Serum phosphate showed a circadian rhythm in normal subjects, and an attenuated rhythm persisted in primary hyperparathyroidism. These data suggest that both ionic factors and higher centres play important roles in the fine control of PTH (1-84) secretion.
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PMID:The loss of circadian rhythm for intact parathyroid hormone and nephrogenous cyclic AMP in patients with primary hyperparathyroidism. 216

Thirteen patients with mild primary hyperparathyroidism who were taking thiazide diuretics intermittently for periods of up to 18 months were followed up for a mean of 5.3 years. No significant difference was found in either plasma total calcium corrected for albumin or whole blood ionized calcium in these patients between the periods on or off thiazides. We conclude that thiazide diuretics are not contraindicated in such patients.
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PMID:Failure of thiazide diuretics to increase plasma calcium in mild primary hyperparathyroidism. 223

To determine the incidence and causes of hypercalcaemia in a hospital population in Hong Kong, all 29,107 samples received in the laboratory in one year were analysed for plasma calcium and albumin, and samples with a plasma calcium concentration adjusted for albumin greater than 2.55 mmol/l were investigated. Plasma calcium greater than 2.55 mmol/l was found in 462 patients. Repeat samples were received from 302 of these and hypercalcaemia was confirmed in 183. The main causes of hypercalcaemia were malignancy (72.1 per cent), tuberculosis (6.0 per cent), and primary hyperparathyroidism (5.5 per cent). In the malignant hypercalcaemia group, carcinoma of lung was the most common (31.8 per cent) and carcinoma of breast was uncommon (3.0 per cent). Secondary deposits in bone were detected in 35 of the 122 solid tumours. In order to identify the mechanism of hypercalcaemia the contributions of renal tubular reabsorption and increased bone resorption to the plasma calcium concentration were calculated. Increased tubular reabsorption was the main contributor to hypercalcaemia in primary hyperparathyroidism and carcinoma of liver (none of whom had bony metastases) and it contributed significantly to hypercalcaemia in carcinoma of lung without bony metastases and carcinoma of oesophagus. We conclude that in Hong Kong (a) primary hyperparathyroidism is uncommon, (b) tuberculosis is an important cause and (c) humoral factors may be responsible for a relatively high proportion of cases of malignant hypercalcaemia.
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PMID:Incidence, causes and mechanism of hypercalcaemia in a hospital population in Hong Kong. 229 Sep 21

In order to obtain a useful screening index for primary hyperparathyroidism (PHPT), seven patients with PHPT and fifty-one patients with nonparathyroid hypercalcemia (NPHC) were studied retrospectively. Serum calcium, inorganic phosphate (IP), alkaline phosphatase, albumin (Alb), chloride (Cl), total protein, urea nitrogen and creatinine (Cre) were analyzed at the same time. Discriminant analysis using a stepwise variable select method was applied to these patients. A discriminant function (F 1) was derived from three laboratory tests; F 1 = -0.660 x [IP] + 0.142 x [Cl] + 0.564 x [Alb] - 14.4 (PHPT: F 1 greater than 0.641). F 1 had sensitivity of 100% and specificity of 72.5% (14 false positives) in diagnosing PHPT. Next, another discriminant function (F 2) was derived from PHPT and the false positive patients; F 2 = -2.61 x [IP] + 0.286 x [Cl] - 4.24 x [Cre] - 19.3 (PHPT: F 2 greater than 0.412). When F 2 was applied to positive patients by F 1, final sensitivity was 100% and specificity was 98%. This screening method was tested prospectively in fifty-six consecutive samples of hypercalcemia (PHPT 4, NPHC 52), resulting in sensitivity of 100% and specificity of 98%. It was proved that our screening method using two step discriminant functions was very useful to diagnose PHPT.
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PMID:[A screening index for primary hyperparathyroidism using discriminant functions]. 260 57


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