Falsely normal values of intact parathyrin in serum of patients with mild primary hyperparathyroidism?
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Biomedical subjects
Publications and source records attributed to L Scarnecchia.
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This study was performed in order to evaluate the clinical usefulness of the measurement of total serum alkaline phosphatase activity (AP), serum osteocalcin (BGP) and urinary hydroxyproline (OHPr) in assessing bone remodelling in primary hyperparathyroidism. Thirty-two patients with primary hyperparathyroidism were included in the study. No statistically significant differences were observed between the mean values of Z-scores obtained for each marker. Furthermore, an inverse correlation was found between percentage of bone mineral content at the distal radius and both BGP (r = -0.57; p less than 0.05) and AP (r = -0.49; p less than 0.05). The results obtained demonstrate that, contrary to other metabolic bone diseases (e.g. Paget's disease of bone), all three markers examined may be used in clinical practice to evaluate the entity of skeletal turnover in primary hyperparathyroidism.
The study was carried out in order to investigate citrate metabolism (i.e. serum levels, filtered load, tubular reabsorption, total and fasting urinary excretion) in a large group of normal subjects (n = 39) and kidney stone patients (n = 45). We found that mean serum citrate levels and filtered loads were similar in the two groups studied. On the other hand, both the 24-hour urinary citrate and the fasting citrate/creatinine ratio were significantly reduced, whereas the mean tubular reabsorption of citrate appeared to be significantly increased in kidney stone patients in respect to control subjects. A good correlation was found between the fasting and the 24-hour citrate/creatinine ratio in both normal subjects (r = 0.84, p less than 0.001) and kidney stone patients (r = 0.89, p less than 0.001). Our data indicate that the kidney appears to be involved in the pathogenesis of hypocitraturia in kidney stone patients and that a substantial proportion of these patients show a reduced urinary excretion of citrate. Finally, the evaluation of the fasting citrate/creatinine ratio may replace the measurement of the substance on the basis of a 24-hour urine collection.
This study has been carried out in order to evaluate both serum osteocalcin levels in primary hyperparathyroidism and their changes following surgery. Twenty-one consecutive patients were studied (12 females and 9 males, aged 46 +/- 17 years). Preoperatively, a better correlation was found between serum osteocalcin and serum alkaline phosphatase activity (r = 0.79, p less than 0.001) than between serum osteocalcin and the 24-hour urinary hydroxyproline/creatine ratio (r = 0.55, p less than 0.05). Following the surgical removal of hyperfunctioning parathyroid tissue, a modest but significant decrease was observed in the serum levels of osteocalcin; this reached a nadir during the 1st or 2nd day after the removal of the adenoma. The mean levels then tended to rise, so that the values measured on the 7th day after parathyroidectomy (12.4 +/- 2.5 ng/ml) were not significantly different in respect to basal values (13.6 +/- 2.7 ng/ml). A parallel pattern was also noted as concerns the serum alkaline phosphatase activity. On the contrary, mean values of serum immunoreactive parathyroid hormone (243 +/- 78 vs. 58 +/- 11 pmol/l; p less than 0.02) and serum calcium (12.4 +/- 0.5 vs. 9.2 +/- 0.3 mg/dl; p less than 0.01) were significantly reduced and mean values of serum phosphorus (2.4 +/- 0.2 vs. 3.1 +/- 0.2 mg/dl; p less than 0.001) significantly higher in comparison to basal values.(ABSTRACT TRUNCATED AT 250 WORDS)
This study was carried out to evaluate the metabolic consequences of osteosclerotic skeletal metastases of prostatic origin in a homogeneous group of patients. We found significantly increased mean values of serum alkaline phosphatase activity and significantly reduced mean values of serum phosphate, 24-h urinary calcium, fasting calcium excretion and TmP/GFR in cancer patients with respect to age-matched controls. Mean serum immunoreactive parathyroid hormone (iPTH) levels were raised, with two patients showing increased values of the hormone above our normal limits. Our findings indicate that mild secondary hyperparathyroidism is a feature of these patients. However, it cannot be excluded that both the reduced serum phosphate and TmP/GFR values may be related, at least in some cases, to the effects of the tumour itself on tubular reabsorption of phosphate.
This investigation was carried out to evaluate the clinical utility and diagnostic value of serum intact PTH measurement using a recently introduced immunochemiluminometric assay (ICMA). Studies were carried out in 42 normal subjects, 24 patients with primary hyperparathyroidism, 21 patients on chronic maintenance hemodialysis, 8 patients with postsurgical hypoparathyroidism, 7 patients with cancer hypercalcemia and 6 patients with osteomalacia. A good correlation was found in normal subjects between serum ICMA PTH levels and both intact PTH measured by a two-site immunoradiometric assay (n = 42, r = 0.67, p less than 0.001) and a widely used midmolecule radioimmunoassay (n = 21, r = 0.78; p less than 0.001). Similar good correlations were found in primary hyperparathyroidism patients (IC-MA vs immunoradiometric assay r = 0.74; p less than 0.001; ICMA vs midmolecule assay r = 0.77; p less than 0.001). As far as the hypercalcemic conditions were concerned, in 5 patients with mild primary hyperparathyroidism, ICMA PTH levels were in the upper range of those found in normal subjects, even though they were inappropriately high in respect to serum calcium values. However, serum ICMA PTH levels were clearly suppressed or undetectable in the majority of patients with cancer hypercalcemia or postsurgical hypoparathyroidism. Following calcium and EDTA infusions in patients with primary hyperparathyroidism, the behaviour of ICMA PTH levels in general parallelled that of immunoradiometric PTH assay, thus indirectly suggesting the ability of the method to measure the intact molecule.(ABSTRACT TRUNCATED AT 250 WORDS)
A 56-year-old white man was referred for evaluation of severe hypercalcemia following a three-week history of progressive weakness, nausea, and depression. Initial laboratory results showed serum total and ionized calcium (Ca++) values of 5.3 and 2.6 mmol/l, respectively. A short intact PTH assay was immediately performed and an extremely high value was obtained in just 30 min (1315 ng/l, normal values 6.4-70.4). The patient was therefore treated with saline solution and with salmon calcitonin (1200 IU/day, half by continuous i.v. infusion and half by i.m. route) for 10 days. There was a sudden decrease of both Ca++ and intact PTH during the first six days; then there was a trend to reach a steady-state until parathyroidectomy was performed. After withdrawal of calcitonin therapy it was possible to observe a positive uncoupling between bone formation (serum alkaline phosphatase and osteocalcin) and resorption (serum tartrate-resistant acid phosphatase) markers. On day 35 the patient underwent neck exploration, and an enlarged lower left parathyroid gland was removed that on macroscopic examination revealed the presence of a haemorrhagic cyst; microscopic appearance was suggestive of a previous glandular infarction. This is the first time the daily clinical course of a parathyroid crisis has been documented. Furthermore, changes of biomarkers of bone turnover following calcitonin therapy show that high doses of the hormone may cause a prolonged positive uncoupling of the two processes of bone remodeling.
Primary hyperparathyroidism is a quite frequent disease, the incidence of which has been found to increase over the past two decades. At the same time there has been a remarkable change in its clinical presentation; therefore this endocrine disorder earlier considered rare but almost always associated with complications, now appears a quite common and uncomplicated disease. In our series of 150 patients diagnosed between 1966 and 1989 the female/male ratio was found to be 1.77. The ratio has significantly increased (2.09), beginning from 1983; this was mainly due to the availability of a bone densitometer at our Mineral Metabolism Service with consequent greater demand of serum calcium determination as a part of routine metabolic screening for prevention of postmenopausal osteoporosis. Whilst the percentage of patients with renal manifestations of the disease has not significantly changed during these years, the amount of asymptomatic patients (yrs 1966-1983 = 3.7% vs yrs 1984-1989 = 39.7%) has progressively increased to the detriment of patients with skeletal symptoms. Serum intact parathyroid hormone determination by immunoradiometric assay (and possibly by immunochemiluminometric assay) seems to have overcome some of the methodological problems inherent in conventional radioimmunoassay. Surgical treatment of primary hyperparathyroidism is safe and highly effective in experienced hands. Recurrence has been observed only in three cases after resection of parathyroid adenoma, thus indirectly supporting a monoclonal origin of the tumor. Medical behavior (conservative or surgical management) in respect to patients with the mild or asymptomatic form of the disease, especially when diagnosed in old age, is uncertain at this point in time. Future prospective studies carried out on a large number of patients are needed to better clarify this issue.
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