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Biomedical subjects

S W Kooh

Publications and source records attributed to S W Kooh.

8 recordsLinked to original sources

Pathogenesis of rickets in chronic hepatobiliary disease in children.

To investigate whether hepatobiliary rickets is caused by defective intestinal absorption of vitamin D or by impaired hepatic hydroxylation of the vitamin, we studied three children who developed severe rickets, hypocalcemia, and hypophosphatemia, two despite having received 400 to 800 IU vitamin D per day by mouth, and one despite prolonged treatment with 10,000 IU daily. On oral vitamin D therapy, plasma vitamin D and 25-hydroxyvitamin D levels were low. When two children were treated with weekly intravenous doses of 3,000 IU vitamin D to approximate the recommended prophylactic allowance, their plasma calcium and phosphate values improved promptly, the radiographic lesions healed, and the plasma concentrations of vitamin D and 25-hydroxyvitamin D became normal. Our studies indicate that the primary cause of hepatobiliary rickets is intestinal malabsorption of vitamin D, not impairment of the hepatic metabolism of the vitamin.

Biliary Tract Diseases

Keratitis with hypoparathyroidism.

Chronic kiratitis developed in two children with nonsurgical hypoparathyroidism, as part of an autosomal recessive syndrome that included adrenal insufficiency and moniliasis in what was postulated to be an autoimmune disease. The corneal changes may also have been caused by autoimmune mechanism. Activity of the keratitis diminished once the hypoparathyroidism had been brought under control. However, these patients were thought to be at risk for adrenal insufficiency: neither had moniliasis or adrenocortical insufficiency at present, but the features of the hypoparathyroidism adrenal insufficiency-moniliasis syndrome appeared at different ages and in differing sequences.

Adolescent

Vitamin D therapy in hypoparathyroidism and pseudohypoparathyroidism: weight-related dosages for initiation of therapy and maintenance therapy.

The aims of this study were to determine the dose of vitamin D2 that maintains the serum calcium level within the normal range in hypoparathyroid and pseudohypoparathyroid children and to establish a safe and quickly acting dose for initiating therapy in symptomatic patients. The dose requirement for maintenance therapy was studied in 11 patients and initiation therapy was studied in five newly diagnosed hypocalcemic patients. The results show that (1) the maintenance requirement of vitamin D2 is proportional to body weight and averages 2,000 IU (50 microgram)/kg/day for children of all ages and with all types of hypoparathyroid disorders and the (2) in newly diagnosed symptomatic patients, carefully controlled administration of 8,000 IU (200 microgram) vitamin D2/kg/day for the first one to two weeks corrects hypocalcemia quickly and safely.

Adolescent

Response of protracted neonatal hypocalcaemia to 1alpha,25-dihydroxyvitamin D3.

Six infants with protracted hypocalcaemia (5 classed as tetany of the newborn) had a mean plasma-calcium of less than 6-4 mg/dl and raised plasma-inorganic-phosphate. Four had been hypocalcaemic for longer than 2 weeks despite treatment with low phosphate formulae and extra calcium. All the infants were treated with 1alpha,25-dihydroxyvitamin D3 (1alpha,25-(OH)2D3), usually in a dose of 0-05 mug/kg body-weight/day, administered intravenously for 5--12 days. The plasma-calcium levels began to rise within 24 h after starting 1alpha,25-(OH)2D3 treatment, increased above 7-5 mg/dl within 3 days, and reached the normal range within 8 days. Four of the infants remained normocalcaemic when 1alpha,25-(OH)2D3 was discontinued, but two infants became hypocalcaemic again and required long-term treatment. 1alpha,25-(OH)2D3 has been found safe and dependable as treatment for protracted neonatal hypocalcaemia.

Birth Weight

Increased bone mineral content in young adults with familial hypophosphatemic vitamin D refractory rickets.

Seven adults with familial hypophosphatemia have been investigated by histologic and radiographic examination of bone, and estimates of bone mineral status by in vivo neutron activation analysis (IVNAA). Histological examination showed severe osteomalacia and osteosclerosis in all cases. Radiography showed skeletal deformities and other sequelae of severe rickets of childhood in five of the seven cases, with, in addition, thickened well-mineralized bones; the other two showed normal radiographs. IVNAA measurements showed that the first five had greater than normal bone calcium and that the other two had normal values. Thus, in all cases there is a greater than normal total bone tissue (osteoid and mineralized bone together). The quantitative body calcium measurements show clearly that osteosclerosis occurs in familial hypophosphatemia, confirming the opinions based on histological and radiological data. Although there has been occasional reference to this sclerosis in the literature, up to the present it has received little attention.

Adolescent

Treatment of hypoparathyroidism and pseudohypoparathyroidism with metabolites of vitamin D: evidence for impaired conversion of 25-hydroxyvitamin D to 1 alpha,25-dihydroxyvitamin D.

In hypoparathyroidism and pseudohypoparathyroidism, pharmacologic doses of vitamin D correct hypocalcemia, but the mechanism is unknown. In two children with hypoparathyroidism and one with pseudohypoparathyroidism we tested the hypothesis that in these conditions there is a defect in synthesis of 1 alpha,25-dihydroxyvitamin D3, the principal active metabolite of vitamin D. In both conditions, minute doses of the metabolite (0.04 to 0.08 mug per kilogram of body weight per day) quickly corrected hypocalcemia and increased intestinal calcium absorption. On the other hand, the effective dose of 25-hydroxyvitamin D3 to maintain normocalcemia was 3 to 4 mug per kilogram per day in the two conditions. Thus, the dosage ratio of 25-hydroxyvitamin D3 to 1 alpha,25-dihydroxyvitamin D3 approximated 100:1. By contrast this ratio was approximately 3:1 in two infants with vitamin D deficiency, a condition in which optimal metabolism of vitamin D would be expected. These findings suggest an impaired conversion of 25-hydroxyvitamin D to 1 alpha,25-dihydroxyvitamin D in both hypoparathyroidism and pseudohypoparathyroidism.

Administration, Oral