ImogenM.A. Evans

REGULATION OF VITAMIN-D METABOLISM WITHOUT PARATHYROID HORMONE

Abstract Thyroparathyroidectomised (T.P.T.X.) rats on a high-calcium diet were given a low-calcium, low-phosphate diet. There was a pronounced increase in production of 1,25-dihydroxycholecalciferol (1,25-D.H.C.C.), the active metabolite of vitamin D, which was not explained by a fall in plasma-phosphate. Thus, parathyroid hormone is not necessary for the initiation of increased production of 1,25-D.H.C.C. by the kidney, and is therefore not the trophic hormone for this renal endocrine system. A likely determinant of the type of vitamin-D metabolite produced is the intracellular calcium concentration within some critical compartment of the renal cell.

FAMILIAL MEDULLARY THYROID CARCINOMA

Medullary thyroid carcinoma (M.C.T.) is a tumour of the calcitonin-secreting cells of the thyroid gland; it affects both lobes, has a variable malignant potential, and is often familial. Despite the availability of diagnostic plasma-calcitonin immunoassays, the condition is rarely considered in the initial assessment of a patient with a thyroid mass so that the is often disseminated by the time it is diagnosed, inadequate surgery is performed, and family members are not investigated. We studied 22 members of a family with M.C.T. and gave alcohol to provoke calcitonin secretion. 3 (excluding the index case) had raised basal calcitonin levels and the diagnosis of M.C.T. was confirmed at operation; their calcitonin levels became undetectable after total thyroidectomy. 3 others had detectable levels after alcohol stimulation and are being re-screened at regular intervals.

Knochenumbau und Calciumphosphat-Stoffwechsel

Knochen besteht aus Mineral-, Matrix-, Wasser-und Fettanteilen. Den geringsten Fettgehalt finden wir im kompakten Knochen, den grosten Fettgehalt im spongiosareichen Epiphysenknochen (Tabelle 1).