24-h urinary cyclic adenosine 3', 5'-monophosphate/creatinine (cAMP/Cr) ratio was assessed in 10 patients with hypoparathyroidism, 6 with primary hyperparathyroidism, 7 with normocalcemic hypercalciuria and recurrent nephrolithiasis, 14 with osteomalacia, 25 with Paget's disease and 53 with symptomatic postmenopausal osteoporosis. In hypoparathyroid subjects the mean values of 24 h cAMP/Cr ratio were significantly lower than the control values, whereas in patients with parathyroid adenoma the mean values were higher and fell after parathyroid surgery. Patients with nephrolithiasis due to absorptive hypercalciuria showed low or normal cAMP/Cr ratio, whereas in those with osteomalacia and mean values of cAMP/Cr ratio were significantly higher than the control values and decreased after vitamin D treatment. The mean value of the 24 h urine cAMP/Cr ratio was normal in patients with Paget's disease or postmenopausal osteoporosis and increased significantly after long term treatment with calcitonin or diphosphonate. This increase paralleled a significant decrease of calcium plasma level. A significant improvement of fractional calcium absorption was observed in women with postmenopausal osteoporosis at the end of treatment with calcitonin or diphosphonate.

Adolescent↗

PubMedDate not supplied

The osteomalacias.

Osteomalacia is characterized by large osteoid seams and a preserved volume of bone trabeculae. The mineralization of newly formed bone requires adequate concentrations of calcium and phosphate: the Ca.P product has been regarded as a useful, empirical diagnostic test of osteomalacia. It decreases in patients with osteomalacia mainly because they have very low plasma phosphate levels. At present total body bone mineral and total body bone density can be directly measured by whole body absorptiometry, which indicates the lowest total mineral content of the skeleton which can increase quickly after adequate treatment. The main symptoms of osteomalacia are: bone pain; muscular weakness (commonly as pelvic girdle myopathy); Looser-Milkman pseudofractures or more often a pattern of generalized demineralization at X-ray. The main biochemical parameters in osteomalacia include: defective calcium absorption with hypocalcemia and hypocalciuria; defective intestinal phosphate absorption with hypophosphatemia; there is often increased renal phosphate clearance due to hypocalcemia and secondary hyperparathyroidism; elevated alkaline phosphatase and osteocalcin levels; high bone turnover confirmed by kinetic studies carried out with radiocalcium or 99mTc-MDP. An etiological classification of the osteomalacias includes: 1) nutritional osteomalacia: a) inadequate exposure to sunlight and/or insufficient vitamin D intake; b) defective intestinal absorption of vitamin D because of malabsorption syndromes (e.g. jejuno-ileal bypass for obesity).(ABSTRACT TRUNCATED AT 250 WORDS)

Calcification, Physiologic↗

PubMedDate not supplied

[The diagnosis of postmenopausal osteoporosis].

Post-menopausal osteoporosis is a metabolic bone disease which is histologically characterised by a reduction of bone mass with normal mineral content of the remaining bone tissue. In clinical term, the symptoms of disease include pain in the bones, pathological fractures (of the vertebra, femur, wrist) and consequent deformations of the skeletons. X-ray is still the most efficient diagnostic tool, although it is only capable of revealing osteopenia when bone has lost more than 40% of its mineral content. Bone densitometry is an important stage in the diagnosis and study of osteoporosis. It is first performed at the distal extremity of the forearm, then at the lumbar vertebra and head of the femur. Bone mineralometry is also currently used to study the skeleton as a whole (total body absorptiometry). This method, which has a high level of precision and no positioning problems, is able to provide extremely reliable measurements of bone mineral content, in particular during monitoring. It is worth underlining, however, that other bone metabolic diseases, namely osteomalacia, are also characterised by reduced bone density: the level of bone density should therefore not be considered as an expression of bone mass. In biochemical terms, post-menopausal osteoporosis leads to minimum modifications of the phospho-calcium metabolism: only during stages of accelerated bone turnover is it possible to observe a small increase in calciuria, hydroxyprolinuria and serum osteocalcin levels. A prime factor for the diagnosis of post-menopausal osteoporosis is the intestinal calcium absorption test: post-menopausal osteoporosis is characterized by insufficient intestinal calcium transport.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗

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