Alteration of vitamin D metabolism in Mexican-Americans.

Studies were performed to investigate vitamin D metabolism in Mexican-Americans. Groups of 15 whites and 16 Mexican-Americans ranging in age from 18 to 41 years were evaluated. All of them were within 25% of their ideal body weight. Each of them was admitted to the Clinical Research Center of the University of Texas Health Science Center and placed on a daily diet estimated to contain 400 mg calcium and 900 mg phosphate. It was found that whereas serum vitamin D (1.8 +/- 0.5 versus 7.6 +/- 1.3 ng/ml, P less than 0.001) and serum 25-hydroxyvitamin D (9 +/- 1 versus 17 +/- 2 ng/ml, P less than 0.01) were significantly lower and serum 1,25-dihydroxyvitamin D (37 +/- 2 versus 28 +/- 2 pg/ml, P less than 0.001) was significantly higher in the Mexican-Americans than in the whites, serum calcium (9.1 +/- 0.1 versus 9.2 +/- 0.1 mg/dl), magnesium (1.84 +/- 0.07 versus 1.80 +/- 0.07 mEq/liter), and Gla protein (19 +/- 3 versus 21 +/- 2 ng/ml) were not different in the two groups. Urinary calcium (144 +/- 14 versus 124 +/- 16 mg/day), phosphate (672 +/- 51 versus 683 +/- 44 mg/day), sodium (110 +/- 8 versus 99 +/- 9 mEq/day), potassium (43 +/- 4 versus 49 +/- 3 mEq/day), and magnesium (7.3 +/- 0.7 versus 7.7 +/- 0.5 mEq/day) and creatinine clearance (173 +/- 14 versus 154 +/- 7 liters/day) were not different in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Perioperative management of the patient with diabetes mellitus undergoing outpatient or elective surgery.

Perioperative management for elective or outpatient surgical procedures should be tailored to the individual patient with diabetes mellitus. The approach will vary depending on whether the patient is insulin requiring or not and whether recent diabetes control has been good or poor. Elevated blood glucose prior to surgery will often improve with correction of the condition requiring surgery.

Hypercalcemia of malignancy: diagnosis and therapy.

Therapy should be individualized on the basis of patient symptoms, severity of hypercalcemia, and prospects for inducing a remission in the underlying malignancy. We have found the most effective approach to be vigorous hydration of the patient, usually intravenously with normal saline at a rate of 300 to 500 mL/h. Intravenous furosemide is given as needed to prevent fluid overload. If the patient is volume replete and if hypercalcemia persists after 24 to 48 hours of intravenous hydration, calcitonin, 200 MRC units subcutaneously every 12 hours plus prednisone, 20 mg orally four times daily, are added. In most cases, a response is seen shortly after institution of this therapy. Meanwhile, attempts to treat the malignancy are initiated, including palliative radiation therapy for bony metastases. If the patient is still hypercalcemic and symptomatic after seven days of this therapy, treatment with plicamycin is given unless the patient's condition is clearly terminal. At present, use of prostaglandin synthetase inhibitors is not recommended, and bisphosphonates are available only for investigational use.

Production of 1,25-dihydroxyvitamin D3 by human T cell lymphotrophic virus-I-transformed lymphocytes.

The human T cell lymphotrophic virus type I (HTLV-I) has recently been identified in a T cell lymphoma associated with hypercalcemia and increased bone turnover. Since increased serum concentrations of 1,25-dihydroxyvitamin D have been reported in this disease, we have examined the capacity of HTLV-I-infected cord blood lymphocytes to metabolize 25-hydroxyvitamin D3. Our results demonstrate that HTLV-I-infected cells have the capacity to metabolize 25-hydroxyvitamin D3 to a substance that co-migrates with 1,25-dihydroxyvitamin D3 by high performance liquid chromatography over a silica column using either 12% isopropanol in hexane or 5% isopropanol in dichloromethane. The metabolite binds to the 1,25-dihydroxyvitamin D3 receptor in rat osteosarcoma cells and stimulates bone resorption in cultures of fetal rat long bones. Mass spectrometric analysis of the metabolite confirmed the presence of 1,25-dihydroxyvitamin D3. Production of 1,25-dihydroxyvitamin D by lymphoma cells may contribute to the pathogenesis of the hypercalcemia seen in patients with HTLV-I-associated T cell lymphomas.