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Biomedical subjects

A M Parfitt

Publications and source records attributed to A M Parfitt.

At least 181 records · Page 10Linked to original sources
PubMed1980

Hyperparathyroidism following head and neck irradiation.

A history of head and neck irradiation in childhood or adolescence was found in 22 of 130 patients with primary hyperparathyroidism compared with only 12 of 400 control patients, a significant difference (P less than .025). Among 200 patients with a known history of childhood irradiation, biochemical or surgical evidence of hyperparathyroidism was found in ten, a prevalence of 5%. This is at least 30 times the prevalence of hyperparathyroidism in the general population (P less than .025). The data indicate that head and neck irradiation should be regarded as an important risk factor in the subsequent development of hyperparathyroidism.

Adenoma↗
PubMed1978

Osteomalacia: current concepts.

Recently acquired knowledge about vitamin D metabolism has improved our understanding in different varieties of osteomalacia. Many new causes of osteomalacia continue to be found. Radiologic and biochemical changes are not always characteristic and may occasionally be misleading. Bone biopsy after a double tetracycline label is helpful in differentiating osteomalacia from high bone turnover conditions and is recommended in most patients with a generalized rarefying skeletal disorder. Even if the underlying disease state cannot be corrected, effective therapy is available in most varieties of osteomalacia. The newer metabolites of vitamin D should soon be generally available to the medical profession. Their use will make treatment of osteomalacia more individualized and specific.

Bone Development↗
PubMed1977

Primary hyperparathyroidism. A cause of hypercalciuria and renal stones in patients with medullary sponge kidney.

Three patients with nephrolithiasis were found to have both medullary sponge kidney (MSK) and primary hyperparathyroidism. In all cases, urine calcium excretion returned to normal after parathyroidectomy. The passage of stones was abolished for more than 20 years in one case and for more than 12 years in another. The available data suggest that many patients with MSK are asymptomatic and that the risk of stone formation is increased by an associated metabolic abnormality such as hypercalciuria or hyperparathyroidism.

Adult↗
PubMed1977

The cellular basis of bone turnover and bone loss: a rebuttal of the osteocytic resorption--bone flow theory.

There is now sufficient evidence to conclude that the osteocytic resorption--bone flow theory of bone turnove is untenable. According to this theory bone is resorbed not from the surface by osteoclasts but from within by osteocytes, towards which bone flows through tissue space away from bone forming surfaces. The need to invoke resorption by osteocytes stems from the belief that too few osteoclasts are present to account for normal bone resoption, a belief which reflects unawareness of the enormous capacity of the osteoclast and the rapidity of its advance. The belief that osteocytes resorb substantial amounts of bone rests on invalid conclusions from indirect techniques, various artifacts of specimen processing and unawareness of the microscopic characteristics of woven bone. Osteocytes enlarge their lacunae by resorbing bone only as a prelude to resorption from the surface, the osteocyte and osteoclast working together as a resorbing unit. The belief that bone can flow is incompatible both with the physical properties of bone and with a substantial body of evidence relating to Haversian remodelling; the experimental data purporting to demonstrate such flow can all be explained by conventional concepts of bone turnover.

Animals↗
PubMed1976

Primary diffuse microscopical hyperplasia of the parathyroid glands: surgical importance.

In two of 182 patients with verified primary hyperparathyroidism, microscopical hyperplasia was present in all parathyroid glands that were normal in size or only slightly enlarged. All parathyroid glands in another two patients showed microscopical hyperplasia and varied from a normal size of 190 mg. In seven additional patients, microscopical hyperplasia was present in one, several, or all parathyroid glands, which varied in weight from normal to 350 mg. Familial hyperparathyroidism or multiple endocrine neoplasia was evident in five of 11 patients. Contributing to difficulties was the experience in five patients in whom removal of mildly enlarged parathyroid glands corrected hypercalcemia, but definite microscopical abnormalities were not evident by routine histologic study of the glands. Thus, there appears to be a spectrum of abnormalities relative to size and microscopical changes in parathyroid glands of patients with primary hyperparathyroidism. The surgeon should be aware of these patterns of parathyroid hyperplasia that require a search for a fifth parathyroid gland and a subtotal parathyroidectomy.

Adult↗