the patients had had pathological fractures. All patients except one had a daily calcium intake of less than 50 mg daily, and a dietary vitamin D intake ofless than 50 IU daily. One patient was taking regular supplements of vitamin D. All had plasma urea and creatinine concentrations within the normal range for our laboratory. Seventeen age and sex matched healthy volunteers were also studied as controls. All controls had body weights within 10% of the average body weight appropriate for height (Geigy Scientific Tables).A fasting venous blood sample was collected from each patient without stasis. Blood was allowed to clot and centrifuged immediately at 4°C. Serum was aliquoted and stored a -20°C for PTH, 25 OHD, and 1,25(OH)2D assays. Plasma calcium and albumin concentrations, and phosphate, and alkaline phosphatase activities were measured by a SMAC Technicon autoanalyser (Technicon, Baskingstoke, UK).Serum 25 OHD was measured by the method described by Preece et al 'and PTH was measured by a radioimmunoassay with an antibody directed against the mid molecular fragment of PTH as described by Roos et al 4; 17f estradiol was measured by a double antibody radioimmunoassay. 1,25(OH)2D was measured by the method described by Reinhardt et al.5

SUMMARY.Plasma calcium, serum 25 hydroxyvitamin 0 [25(OH)D], 1,25 dihydroxyvitamin D[I,25(OH)2D] and parathyroid hormone (PTH) have been measured in pregnant and newborn Caucasians and Asians. Calcium and 25(OH)D concentrations were lower in Caucasian than in Asian women at all four stages (three trimesters and during labour) of pregnancy. PTH concentrations were greater in Asian than in Caucasian women during the three trimesters, but not at labour, and increased in both groups through pregnancy, without a concomitant change in plasma calcium concentrations. There was a significant inverse correlation between calcium and PTH, as well as 25(OH)D and PTH, concentrations. These data demonstrate the presence of progressive 'hyperparathyroidism' during pregnancy in Caucasian and Asian women. The higher PTH concentrations in Asian women may reflect the necessity of maintaining adequate plasma calcium concentrations through PTH-induced osteolysis in the face of vitamin 0 deficiency. Relative hyperparathyroidism in Asians may contribute to net loss of calcium from the skeleton and osteopenia in Asian women. Calcium, 25(OH)D and 1,25(OHhD concentrations were lower, and those of PTH higher, in Asian newborns compared with Caucasian newborns. Serum 1,25(OHhD concentrations in the Asian newborn, though lower than respective maternal levels, were comparable with normal adult levels, indicating that 1,25(OHhD biosynthesis is stimulated in the Asian newborn to compensate for the low serum 25(OH)D concentrations.It has been demonstrated that asymptomatic Asian immigrants in the United Kingdom may have subclinical hypovitaminosis 0 and secondary hyperparathyroidism.i":' It has also been shown that the concentrations of 25 hydroxyvitamin 0 [25(OH)D] in cord blood are significantly lower than those in maternal serurn.v" These facts raise the possibility that secondary hyperparathyroidism may be frequent in Asian women during pregnancy, and that these women's infants may also have secondary hyperparathyroidism. It has previously been suggested that serum concentrations of PTH increase during pregnancyr':" this Correspondence: Dr P Dandona, Metabolic Unit, Department of Chemical Pathology and Human Metabolism, Royal Free Hospital, Pond Street, London NW3 20G, UK. 22 observation has, however, been challenged by other workers.?'!" To our knowledge, there is only one previous study which has compared 25(OH)D and PTH concentrations in the serum of pregnant Caucasian and Asian women. I I In this study, radioimmunoassays of PTH were carried out by the method of Rosselin et al. ,12 and failed to detect any differences in serum PTH between Asian and Caucasian women. Since we and others, using more recent radioimmunoassay methodology, 1-] have reported frequent secondary hyperparathyroidism in non-pregnant Asians, it is clear that 25(OH)D-calcium-PTH relationships during pregnancy need to be re-examined. Finally, no data are available about 1,25 dihydroxyvitamin D [1,25(OHhD] concentrations in Asian and Caucasian women at term and their ne...

No abstract

The relationship among serum vitamin D metabolites, PTH, and osteocalcin concentrations was investigated in 20 elderly subjects. All except 2 had subnormal 25-hydroxyvitamin D concentrations. Eighteen (90%) had subnormal serum 1,25-dihydroxyvitamin D [1,25-(OH)2D] concentrations, while 8 subjects (40%) had elevated PTH concentrations. There was a highly significant inverse relationship between PTH and 1,25-(OH)2D concentrations. Serum osteocalcin concentrations were not elevated in any subject, and in fact, the mean osteocalcin concentration was in the lower part of the normal range. These data indicate no compensatory increase in 1,25-(OH)2D in response to secondary hyperparathyroidism and no increase in osteocalcin in response to hypersecretion of PTH in the elderly. These 2 defects may contribute to the bone disease of the elderly.

Prior to the widespread use of continuous glucose monitoring (CGM), knowledge of the effects of exercise in type 1 diabetes (T1D) was limited to the exercise period, with few studies having the budget or capacity to monitor participants overnight. Recently, CGM has become a staple of many exercise studies, allowing researchers to observe the otherwise elusive late post-exercise period. We performed a strategic search using PubMed and Academic Search Complete. Studies were included if they involved adults with T1D performing exercise or physical activity, had a sample size greater than 5, and involved the use of CGM. Upon completion of the search protocol, 26 articles were reviewed for inclusion. While outcomes have been variable, CGM use in exercise studies has allowed the assessment of post-exercise (especially nocturnal) trends for different exercise modalities in individuals with T1D. Sensor accuracy is currently considered adequate for exercise, which has been crucial to developing closed-loop and artificial pancreas systems. Until these systems are perfected, CGM continues to provide information about late post-exercise responses, to assist T1D patients in managing their glucose, and to be useful as a tool for teaching individuals with T1D about exercise.