Biochemical indices of osteomalacia in pregnant Asian immigrants in Britain.
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Serum calcium, phosphate and alkaline phosphatase, and urinary calcium excretion were examined during the second trimester of uncomplicated normal pregnancy in Asian immigrants to Britain and in local Caucasians. The mean serum calcium was significantly lower in Asians than in Caucasians, and the mean serum alkaline phosphatase was significantly higher in Asians. The geometric mean of the urinary calcium excretion was highly significantly lower in Asians than in Caucasians. The variances of the serum calcium, serum alkaline phosphatase, and urine calcium excretion did not differ significantly in the two populations. This indicates that there is a shift in values of immigrant Asians as a group compared with Caucasians. A comparison with figures obtained on normal nonpregnant persons of both suggests that the shift is not an inherent feature of the Asian population. (+info)
Use of ultrasonography in the diagnosis of osteomalacia: preliminary results on experimental osteomalacia in the rat.
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This study was performed to investigate the ability of ultrasonographic technique to distinguish osteomalacia from normal bone with the same mineral content. Ten rats with experimentally induced osteomalacia (group A) and 12 control rats having similar body size and weight (group B) were studied. Histomorphometric analysis confirmed the presence of osteomalacia in two rats from group A and showed normally mineralized bone in two rats from group B. Whole body bone mineral density, measured by dual-energy x-ray absorptiometry, was similar in the two groups (86 +/- 6 mg/cm2 in group A and 89 +/- 4 mg/cm2 in group B). The velocity of the ultrasound beam in bone was measured by densitometer at the first caudal vertebra of each rat. The velocity was measured when the first peak of the waveform reached a predetermined minimum amplitude value (amplitude-dependent speed of sound) as well as at the lowest point of this curve before it reaches the predetermined minimum amplitude (first minimum speed of sound). Although the amplitude-dependent speed of sound was similar in the two groups (1381.9 +/- 11.8 m/s in group A and 1390.9 +/- 17.8 m/s in group B), the first minimum speed of sound was clearly different (1446.1 +/- 8.9 m/s in group A and 1503.3 +/- 10.9 m/s in group B; P < 0.001). This study shows that ultrasonography could be used to identify alterations in bone quality, such as osteomalacia, but further studies need to be carried out before this method can be introduced into clinical practice. (+info)
Bone histology in patients with nephrotic syndrome and normal renal function.
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BACKGROUND: The prevalence of metabolic bone disease in patients with nephrotic syndrome (NS) at normal level of renal function remains uncertain. METHODS: To address this issue, we studied 30 patients (20 men and 10 women, mean age 27.3 +/- 11.7 years) with NS who had normal renal function (mean creatinine clearance 103 +/- 4 ml/min). We evaluated their serum calcium, phosphorus, alkaline phosphatase, immunoreactive parathyroid hormone (iPTH), vitamin D metabolites, urinary calcium, and skeletal survey. The extent of bone mineralization was analyzed by histomorphometric analysis of iliac crest bone biopsy specimens in all patients. The findings on bone histology were correlated with biochemical parameters. RESULTS: The mean duration of NS was 35.5 +/- 26.9 months, with a protein excretion of 7.3 +/- 3.2 g/24 hr and a serum albumin of 2.2 +/- 0.8 g/dl. Total serum calcium was 7.8 +/- 0.8 mg/dl, whereas ionized calcium was 5.7 +/- 0.7 mg/dl, phosphorus 3.2 +/- 1.2 mg/dl, and alkaline phosphatase 149 +/- 48.6 U/liter. Serum iPTH levels were normal in all except two patients. The mean serum 25-hydroxyvitamin D [25(OH)D] level was 3.9 +/- 1.2 ng/ml (normal 15 to 30 ng/ml), whereas 1,25-dihydroxyvitamin D was 24 +/- 4.7 pg/ml (normal 16 to 65). There was an inverse correlation between serum levels of 25(OH)D and the magnitude of proteinuria (r = -0.42, P < 0.05). The mean 24-hour urinary calcium excretion was 82 +/- 21 mg/day. The skeletal survey was normal in all patients. Bone histology was normal in 33.3% of the patients, whereas 56.7% had isolated osteomalacia (OSM), and 10% had an increased bone resorption in association with defective mineralization. The severity of OSM measured by mineralization lag time correlated linearly with the duration (r = 0.94, P < 0.0001) and the amount (r = 0.97, P < 0.0001) of proteinuria. All patients with NS for more than three years had histological changes. Patients with OSM had lower 25(OH)D and serum albumin as compared with those with normal histology (P < 0.005). Bone mineralization had no significant correlation with serum iPTH, divalent ions, or vitamin D levels. CONCLUSIONS: OSM is a frequent finding in adult patients with NS, even at a normal level of renal function. Its severity correlates with the amount and duration of proteinuria. (+info)
Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety.
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For adults, the 5-microg (200 IU) vitamin D recommended dietary allowance may prevent osteomalacia in the absence of sunlight, but more is needed to help prevent osteoporosis and secondary hyperparathyroidism. Other benefits of vitamin D supplementation are implicated epidemiologically: prevention of some cancers, osteoarthritis progression, multiple sclerosis, and hypertension. Total-body sun exposure easily provides the equivalent of 250 microg (10000 IU) vitamin D/d, suggesting that this is a physiologic limit. Sailors in US submarines are deprived of environmentally acquired vitamin D equivalent to 20-50 microg (800-2000 IU)/d. The assembled data from many vitamin D supplementation studies reveal a curve for vitamin D dose versus serum 25-hydroxyvitamin D [25(OH)D] response that is surprisingly flat up to 250 microg (10000 IU) vitamin D/d. To ensure that serum 25(OH)D concentrations exceed 100 nmol/L, a total vitamin D supply of 100 microg (4000 IU)/d is required. Except in those with conditions causing hypersensitivity, there is no evidence of adverse effects with serum 25(OH)D concentrations <140 nmol/L, which require a total vitamin D supply of 250 microg (10000 IU)/d to attain. Published cases of vitamin D toxicity with hypercalcemia, for which the 25(OH)D concentration and vitamin D dose are known, all involve intake of > or = 1000 microg (40000 IU)/d. Because vitamin D is potentially toxic, intake of >25 microg (1000 IU)/d has been avoided even though the weight of evidence shows that the currently accepted, no observed adverse effect limit of 50 microg (2000 IU)/d is too low by at least 5-fold. (+info)
Is low plasma 25-(OH)vitamin D a major risk factor for hyperparathyroidism and Looser's zones independent of calcitriol?
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BACKGROUND: Recent reports suggest that calcitriol might not be the sole active metabolite of vitamin D and that plasma concentrations of 25-(OH)vitamin D (25OHD) are often abnormally low in hemodialysis patients. We have therefore evaluated plasma 25OHD as a risk factor for parathyroid hormone (PTH) hypersecretion and radiological bone disease. We carried out a cross-sectional study during the month of September in an Algerian dialysis center of 113 patients who were not taking supplements of alphacalcidol or calcitriol. METHODS: Plasma 25OHD, calcitriol, PTH, calcium, phosphate, bicarbonate, and aluminum were measured, and x-rays of the hands and pelvis were obtained for evaluation of subperiosteal resorption and Looser's zones. RESULTS: The median plasma 25OHD was 47.5 nmol/liter (range 2.5 to 170.0). Univariate analysis showed that plasma PTH was correlated positively with months on maintenance dialysis and negatively with plasma 25OHD, calcitriol, calcium, bicarbonate and aluminum, but not with that of phosphate. plasma 25OHD was positively correlated with calcium and calcitriol. Using multiple regression analysis, only plasma 25OHD (negative) and the duration on maintenance dialysis (positive) were independently linked to plasma PTH. The prevalence of isolated subperiosteal resorption (ISR) was 34%, and that of the combination of resorption with Looser's zones (CRLZ) was 9%; thus, only 57% of the patients had a normal x-ray appearance. These groups were comparable with regards to age, gender, and duration on dialysis. When the biochemical measurements of the patients with CRLZ were compared with those from patients without radiological lesions, plasma 25OHD was the only parameter to show a statistically significant difference, being significantly lower in the CRLZ group (26 +/- 18 vs. 57 nmol/liter, ANOVA, P < 0.004). Plasma 25OHD was also significantly lower in the ISR group (44, P < 0.05) than in the normal x-ray group, and plasma Ca (P < 0.003) and bicarbonate (P < 0.02) were lower. Logistical analysis showed that the presence of resorption was independently linked only with plasma PTH. Looser's zones and subperiosteal resorption were not seen in patients with plasma 25OHD of more than 40 (Looser's zones) and more than 100 nmol/liter (subperiosteal resorption). The optimal range for intact PTH in hemodialysis patients with mild aluminum overload is 10 to 25 pmol/liter. We found that plasma PTH was inappropriately high only when plasma 25OHD was less than 100 nmol/liter. With a plasma 25OHD of between 100 and 170 nmol/liter, hypercalcemia was present with a plasma PTH of less than 10 pmol/liter in only one case. CONCLUSIONS: This cross sectional study shows that low plasma 25OHD is a major risk factor for hyperparathyroidism and Looser's zones. In dialysis patients, we suggest that the plasma levels of 25OHD are maintained around the upper limit of the reference range of sunny countries. (+info)
Bone scintigraphy in renal osteodystrophy.
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Bone scintigraphy with Tc-99m HEDP was performed in 30 patients on maintenance hemodialysis, and the results of quantitative analysis were compared with those of a normal group. To permit this comparison, elevated background activity due to the absence of renal radiotracer excretion was reduced by hemodialysis to levels found in the normals. Histologic proof of renal osteodystrophy had been obtained in all patients. The incidence of radiographic abnormalities was 46%, whereas abnormal scans were found in 25 patients (83%); skeletal lesions were also more pronounced and detected earlier. However, even when the scans appeared normal, the quantitative analysis showed increased skeletal activity in all patients. The total skeletal activity proved to be a good index of the severity of renal osteodystrophy and appeared dependent on both osteomalacia and hyperparathyroidism. These findings show that bone scintigraphy is a sensitive method to detect skeletal involvement in renal osteodystrophy. (+info)
Increased bone strontium levels in hemodialysis patients with osteomalacia.
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BACKGROUND: In this study, we report on the association between increased bone strontium levels and the presence of osteomalacia in end-stage renal failure patients treated by hemodialysis. METHODS: We performed a histologic examination and determined the strontium content and strontium/calcium ratios in bone biopsies of 100 hemodialysis patients recruited from various centers all over the world. Aside from the bone strontium concentration, the bone aluminum content was assessed. The bone zinc concentration, a nonrelevant element for bone toxicity, was also measured. RESULTS: Bone strontium levels and bone strontium/calcium ratios were increased in subjects with osteomalacia when compared with those with the other types of renal osteodystrophy. Bone strontium and bone calcium levels correlated with each other. The slope of the linear regression curve correlating these parameters was much steeper in the osteomalacic group (Y = 2.22X - 120) as compared with the other types of renal osteodystrophy (Y = 0.52X - 5.7). Within the group of patients with osteomalacia, bone strontium levels also significantly correlated with the bone aluminum content (r = 0.72, P = 0.018). No such correlation was found for the other types of renal osteodystrophy. The bone zinc concentration of subjects with normal renal function did not differ significantly from the values noted for the various types of renal osteodystrophy taken as separate groups, nor could increased bone zinc concentrations be associated with a particular bone lesion. CONCLUSIONS: Our data demonstrate an association between osteomalacia and increased bone strontium concentrations in dialysis patients. Further studies are warranted to establish whether strontium plays either a primary, secondary, or contributive role in the development of the latter type of renal osteodystrophy. (+info)
Use of quantitative ultrasonography in differentiating osteomalacia from osteoporosis: preliminary study.
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The aim of this work was to use ultrasonographic technology to differentiate osteoporosis from osteomalacia on the basis of different patterns of the graphic trace. Three patients with osteomalacia and three with osteoporosis, all with the same lumbar spine bone mineral density, were studied. The velocity of the ultrasound beam in bone was measured by a DBM Sonic 1,200/I densitometer at the proximal phalanges of the hands in all the patients. The ultrasound beam velocity was measured when the first peak of the waveform reached a predetermined minimum amplitude value (amplitude-dependent speed of sound) as well as at the lowest point prior to the first and second peaks, before they reached the predetermined minimum amplitude value (first and second minimum speeds of sound). The graphic traces were further analyzed by Fourier analysis, and both the main frequency (f0) and the width of the peak centered in the f0 (full width at half maximum) were measured. The first and second minimum speeds of sound were significantly lower in the patients with osteomalacia than in the osteoporosis group. The first minimum speed of sound was 2,169 +/- 73 m/s in osteoporosis and 1,983 +/- 61 m/s in osteomalacia (P < 0.0001); the second minimum peak speed of sound was 1,895 +/-59 m/s in osteoporosis and 1,748 +/- 38 m/s in osteomalacia (P < 0.0001). The f0 was similar in the two groups (osteoporosis, 0.85 +/- 0.14 MHz; osteomalacia, 0.9 +/- 0.22 MHz; P = 0.72), and the full width at half maximum was significantly higher in the osteomalacia patients (0.52 +/- 0.14 MHz) than in the osteoporosis patients (0.37 +/- 0.15 MHz) (P = 0.022). This study confirms that ultrasonography is a promising, noninvasive method that could be used to differentiate osteoporosis from osteomalacia, but further studies should be carried out before this method can be introduced into clinical practice. (+info)