Alendronate increases lumbar spine bone mineral density in patients with Crohn's disease

BACKGROUND & AIMS

Low bone mineral density (BMD) is a common complication of Crohn's disease and may lead to increased morbidity and mortality because of fractures. We investigated the effect of treatment with the bisphosphonate alendronate on bone mass and markers of bone remodeling in patients with Crohn's disease.

METHODS

A 12-month double-blind, randomized, placebo-controlled trial examined the effect of a 10-mg daily dose of alendronate. Thirty-two patients with a bone mass T score of -1 of the hip or lumbar spine were studied. The main outcome measure was the difference in the mean percent change in BMD of the lumbar spine measured by dual-energy x-ray absorptiometry. Secondary outcome measures included changes in BMD of the hip and total body and biochemical markers of bone turnover (S-osteocalcin, urine pyridinoline, and urine deoxypyridinoline excretion).

RESULTS

Mean (+/-SEM) BMD of the lumbar spine showed an increase of 4.6% +/- 1.2% in the alendronate group compared with a decrease of 0.9% +/- 1.0% in patients receiving placebo (P < 0.01). BMD of the hip increased by 3.3% +/- 1.5% in the alendronate group compared with a smaller increase of 0.7% +/- 1.1% in the placebo group (P = 0.08). Biochemical markers of bone turnover decreased significantly in the alendronate group (P < 0.001). Alendronate was well tolerated, and there was no difference in adverse events among treatment groups.

CONCLUSIONS

Treatment with alendronate, 10 mg daily, significantly increased BMD in patients with Crohn's disease and was safe and well tolerated.

Effect of intravenous ranitidine and omeprazole on intestinal absorption of water, sodium, and macronutrients in patients with intestinal resection

BACKGROUND

H2 receptor blockers and proton pump inhibitors reduce intestinal output in patients with short bowel syndrome.

AIMS

To evaluate the effect of intravenous omeprazole and ranitidine on water, electrolyte, macronutrient, and energy absorption in patients with intestinal resection.

METHODS

Thirteen patients with a faecal weight above 1.5 kg/day (range 1.7-5.7 kg/day and a median small bowel length of 100 cm were studied. Omeprazole 40 mg twice daily or ranitidine 150 mg twice daily were administered for five days in a randomised, double blind, crossover design followed by a three day control period with no treatment. Two patients with a segment of colon in continuation were excluded from analysis which, however, had no influence on the results.

RESULTS

Omeprazole increased median intestinal wet weight absorption compared with no treatment and ranitidine (p<0.03). The effect of ranitidine was not significant. Four patients with faecal volumes below 2.6 kg/day did not respond to omeprazole; in two absorption increased by 0.5-1 kg/day; and in five absorption increased by 1-2 kg/day. Absorption of sodium, calcium, magnesium, nitrogen, carbohydrate, fat, and total energy was unchanged. Four high responders continued on omeprazole for 12-15 months, but none could be weaned from parenteral nutrition.

CONCLUSION

Omeprazole increased water absorption in patients with faecal output above 2.50 kg/day. The effect varied significantly and was greater in patients with a high output, but did not allow parenteral nutrition to be discontinued. Absorption of energy, macronutrients, electrolytes, and divalent cations was not improved. The effect of ranitidine was not significant, possibly because the dose was too low.

Clinical, social and rehabilitation status of long-term home parenteral nutrition patients: results of a European multicentre survey

BACKGROUND

Home parenteral nutrition (HPN) is a lifesaving treatment in patients with intestinal failure. Dependency of nutritional support becomes permanent for the majority of patients who had received HPN for at least 2 years. The alternative to long term HPN in selected patients is intestinal transplantation.

AIMS

To study some of the clinical, social and rehabilitation aspects of long-term HPN treatment.

METHODS

A survey was performed in nine European HPN centres. The questionnaire covered epidemiologic data, underlying diseases, intestinal anatomy, nutritional support and status, marital status, rehospitalization rate, HPN complications, rehabilitation score, drugs use, coexistent diseases and interest in intestinal transplantation. For some items, data were collected within 12 months prior to the evaluation.

RESULTS

This survey included 228 patients with a median age of 49 years. The median duration of HPN was 7 years (range 2--24 years). Short bowel length less than 100 cm was reported in 65% of patients with a predominance of end-jejunostomy or jejuno-colonic anastomosis. Global subjective nutritional status was normal in 79% of the patients, who were supplied with a mean number of 5.6 bags of parenteral nutrition weekly. Rehospitalizations within the 12 months prior to evaluation accounted for a mean period of 23 days and were due to HPN complications in half of the cases. Catheter-related sepsis was the most frequent HPN-complication. Bone metabolism disorders, which seemed to be more common than liver diseases, were directly related to HPN duration. One-third of the HPN patients was regularly consuming analgesics or opiates. HPN impair complete rehabilitation status but may improve the status of patients who had a very low rehabilitation score before starting HPN. An interest of intestinal transplantation was noted in only 10% of medical teams and in 8% of HPN patients.

CONCLUSIONS

This study is the largest European survey on long-term HPN patients with long standing or permanent intestinal failure. Data enlighten clinical, social and rehabilitation aspects of patients who could face the option of intestinal transplantation in the future.

Does carbamazepine cause disturbances in calcium metabolism in epileptic patients?

Calcium metabolism was examined in 30 adult epileptic outpatients on carbamazepine monotherapy. The patients had a normal bone mass, evaluated both on the forearm (100 +/- 13 of normal) and on the total skeleton (102 +/- 15), and normal serum concentrations of 25OHD. The serum calcium was decreased (P less than 0.001) and the serum alkaline phosphatase increased (P less than 0.001). The clinical significance of our study is that monotherapy with carbamazepine does not have the side effects on bone metabolism known as "anticonvulsant osteomalacia". Our results further question the connection between liver enzyme induction and anticonvulsant osteomalacia, since carbamazepine possesses the same potency of liver enzyme induction as phenytoin. Further studies on epileptic outpatients will be necessary in order to elucidate the connection between treatment with anticonvulsant drugs and anticonvulsant osteomalacia.

Bone mineral content in patients with Crohn's disease. A longitudinal study in patients with bowel resections

BACKGROUND

Low bone mineral content (BMC) has been reported in patients with inflammatory bowel disease. The aim of the present study was to measure BMC in patients with Crohn's disease.

METHODS

BMC was monitored for a mean period of 5.5 years in 108 patients. The patients were divided into two groups: group A, patients with the colon preserved; group B, patients with a resected colon. The mean length of the resected small intestine was 90 cm.

RESULTS

The BMC of the lumbar spine expressed as Z-score ((actual value-mean)/s) was significantly reduced: mean Z-score for group A, -0.51, P < 0.05; group B, -0.80, P < 0.001. The BMC of the femoral neck was significantly reduced: mean Z-score for group A, -1.24, P < 0.001; group B, -1.23, P < 0.001. A Z-score below -2.0 of spine or femoral neck BMC was found in 10% and 23% of the patients, respectively. The BMC of the femoral neck decreased significantly in both groups during the study period (group A, -2.2%, P < 0.001; group B, -1.21%, P < 0.05). The BMC of the lumbar spine did not change. There was an inverse correlation between the initial Z-score and the rate of change in BMC (P < 0.05). We found no correlation between Z-score or change in BMC and period of prednisolone treatment. Moreover, there was no correlation between the length of the resected small intestine and BMC or annual percentage change in BMC.

CONCLUSION

At inclusion the BMC of the spine and femoral neck was low in patients with Crohn's disease. During the study significant bone loss was only demonstrated in the femoral neck. BMC or rate of change in BMC was not related to treatment with steroids or length of the resected small intestine.

Body composition by dual-energy X-ray absorptiometry in patients with Crohn's disease

BACKGROUND

To study body composition at the whole-body level in patients with Crohn's disease and a history of intestinal resection compared with healthy controls, we performed a cross-sectional study using dual-energy X-ray absorptiometry (DXA).

METHODS

Thirty-one patients, 13 men and 18 women, were included. They had a history of Crohn's disease for a mean period of 20 years (range, 4-45 years). All patients had undergone intestinal resections. The colon had been resected in 24 patients, and the mean length of the resected small intestine was 97 cm (range, 0-305 cm). At the time of investigation the Crohn's disease had been in remission for at least 24 months. Patients presented with significantly increased faecal volume and faecal fat excretion. A group of 69 women and 19 men were investigated with DXA and used as reference group. The fat-free mass (FFM), fat mass (FM), percentage fat mass (FM%), and total body mineral content (TBMC) were measured by DXA, and the results were expressed as a z-score.

RESULTS

The mean z-score of the body mass index (BMI) was significantly reduced to -0.35 (P=0.036). The FFM was significantly reduced with a mean z-score of -1.74 (P=0.0001). The FM was unchanged (z-score, 0.12; P=0.42). However, FM expressed as percentage of body weight was significantly increased, with a z-score of 0.88 (P=0.001). The TBMC was significantly decreased, with a mean z-score of -1.42 (P=0.0001). There was positive direct correlation between the BMI and TBMC z-scores. There was no correlation between malabsorption and body composition variables.

CONCLUSION

Patients with clinically quiescent Crohn's disease showed significant changes in body composition, with low BMI, significant loss of FFM, and unchanged FM. However, when expressed as percentage of body weight, FM was significantly increased. The TBMC was significantly reduced.

Unchanged biochemical indices of bone turnover despite fluctuations in 1,25-dihydroxyvitamin D during the menstrual cycle

To examine the effect of endogenous oestrogens on calcium metabolism during the menstrual cycle, fasting blood and urinary samples were obtained every day throughout the menstrual cycle in 5 young women. Bone turnover was estimated by serum alkaline phosphatase and fasting urinary excretions of hydroxyproline and calcium. Serum levels of oestradiol (E2), oestrone (E1), and androstenedione (A) showed the well known cyclic fluctuations, the serum 1,25-dihydroxyvitamin D (1,25(OH)2D) nearly doubled from the early follicular phase to the time of ovulation, although 25-hydroxyvitamin D (25OHD) and 24,25-dihydroxyvitamin D (24,25(OH)2D) were almost unchanged. No correlation between the rise in the serum 1,25(OH)2D level and the measured parameters of calcium metabolism was observed. In view of these findings, the 1,25(OH)2D3 serum concentration measured in women with functioning ovaries can only be interpreted in the context of the menstrual cycle. The published normal range in women for the metabolite may also require reinterpretation.

Serum vitamin D metabolites in epileptic patients treated with 2 different anti-convulsants

The serum concentrations of the vitamin D metabolites 25-hydroxyvitamin D (25OHD), 24,25-dihydroxyvitamin D (24,25(OH)2D), and 1,25-dihydroxyvitamin D (1,25(OH)2D) were measured in 18 epileptic patients and 10 controls. The patients were divided according to the anti-convulsant treatment they had been receiving for at least 1 year: 9 patients had received phenytoin and 9 patients carbamazepine, as the sole anti-convulsant therapy. The serum 25OHD was decreased in the patients on phenytoin (P less than 0.01), whereas the other serum vitamin D metabolites were normal. Moreover, serum alkaline phosphatase was increased (P less than 0.001) and serum calcium was decreased (P less than 0.001) in this patient group. In the patient group treated with carbamazepine (a negligible, liver inductor), changes in serum 25OHD and serum alkaline phosphatase were less pronounced (P less than 0.05), but the same degree of hypocalcaemia (P less than 0.001) was present. Our data suggest that liver induction in epileptic patients on anti-convulsant drugs cannot explain the pathophysiology behind anti-convulsant osteomalacia.

Effect of vitamin D2 and D3 on bone-mineral content in carbamazepine-treated epileptic patients

In order to clarify whether carbamazepine causes disturbances in calcium and bone metabolism were examined the effect of vitamin D2 or D3 in 30 epileptic outpatients. They had been treated for at least 1 year with carbamazepine given as monotherapy. The local bone mineral in the forearms and the total bone mineral was measured before and during treatment with the vitamins (4000 IU/day) for 24 weeks. The bone mineral was not significantly different from controls before the study and it remained unchanged in both treatment groups during the study periods. Similarly, the biochemical indices of bone metabolism were virtually unchanged during the treatment period. We, thus, conclude that epileptic patients on carbamazepine monotherapy have normal bone metabolism.

Different actions of vitamin D2 and D3 on bone metabolism in patients treated with phenobarbitone/phenytoin

In 22 epileptic outpatients treated for at least 1 year with phenobarbitone/phenytoin the local and total bone mass, together with serum and urinary indices of calcium metabolism, were measured before and during treatment with either vitamin D2 or D3, 4,000 IU daily for 24 weeks. The results showed a distinct difference in the action of the two vitamins on bone metabolism during anti-convulsant treatment. The bone mass increased during treatment with vitamin D2, whereas the vitamin D3-treated patients showed unchanged values of bone mass, but an increased excretion rate of calcium, probably caused by increased intestinal calcium absorption. The data demonstrate that vitamins D2 and D3 (or their metabolites) have quantitative different effects in patients treated with phenobarbitone/phenytoin.

A selective and simplified radioimmunoassay of 25-hydroxyvitamin D3

A simple, non-chromatographic and selective assay for determination of 25OHD3 in serum is described. The serum sample is deproteinated with acetonitrile and the supernatant purified over a small prepacked cartridge, Sep-pak. In the eluate from the cartridge, 25OHD3 is measured by radioimmunoassay. The selectivity of the assay for 25OHD3 is improved by adding vitamin D2 to the antiserum; the assay is thus capable of measuring 25OHD3 in serum samples containing up to a ratio of 25OHD2/25OHD3 equal to 150. The simplicity, speed and the small amount of sample needed (0.5 ml) make this method suitable for use in a routine clinical laboratory. Because of its selectivity for 25OHD3 the assay is a necessary prerequisite in the further investigation of metabolic discrimination between vitamins D2 and D3.

Serum alkaline phosphatase during hormone treatment in early postmenopausal women. A model for establishing optimal prophylaxis and treatment in postmenopausal osteoporosis

We propose a new model for use in establishing optimal treatment of postmenopausal osteoporosis. When hydroxyproline is taken as an estimate of bone resorption and alkaline phosphatase (ALP) of bone formation, the model indicates that the difference between hydroxyproline and ALP is reflected in the negative calcium balance, and thus the decline in bone mineral content (BMC). Since BMC increases during oestrogen treatment in postmenopausal women, in whom ALP declines gradually, it is postulated that this only happens because of a rapid decline in hydroxyproline. This decline together with BMC, must be dose-related since changes in ALP are uncorrelated to the oestrogen dose. This model fits the generally accepted opinion that the effect of oestrogen on bone loss in postmenopausal osteoporosis is limited, declines with age, and is dose-related. The model indicates that oestrogen treatment should be introduced early after the menopause in order to obtain the optimum prophylactic effect.

The metabolism of [75Se]selenite in patients with short bowel syndrome

BACKGROUND

Patients on home parenteral nutrition (HPN) require significantly higher amounts of selenium compared with controls. The purpose of the present study was to investigate if selenium deficiency of patients with short bowel syndrome is caused by selenium malabsorption or by excessive intestinal or renal loss.

METHODS

The metabolism of [75Se]selenite was investigated in eight selenium-depleted short bowel patients on HPN and in six control subjects. The isotope was given orally, and in a subsequent study as bolus injection or as 12-hour IV infusion.

RESULTS

The fractional intestinal absorption of selenium was significantly reduced in the patients (2% to 58%, median 20%) when compared with the reference group (79% to 91%, median 82%) (p < .001). Within the group of patients we found a positive significant correlation between fractional selenium absorption and the length of the remaining small intestine (r = 0.95, p < .05). After parenteral [75Se]selenite administration, the patients showed a significantly higher fecal loss and a significantly reduced urinary excretion of 75Se when compared with the controls. Bolus injection vs 12-hour infusion of [75Se]selenite did not affect the cumulative fecal or urinary 75Se excretion in the HPN patients.

CONCLUSIONS

Reduced intestinal selenium absorption is probably the most important cause of the selenium deficiency reported in patients with short bowel syndrome, but increased endogenous intestinal selenium loss and low selenium intake may also contribute. Despite the renal counterregulation, which results in a low urinary selenium excretion, HPN patients need a supply of selenium with their parenteral nutrition.

Representativity of regional to total bone mineral in healthy subjects and 'anticonvulsive treated' epileptic patients. Measurements by single and dual photon absorptiometry

Dual photon (153Gd) and single photon (125I) absorptiometry were used to measure the regional bone mineral content (BMC) and density (BMD), as well as the total body mineral content (TBBM) and density (TBBD), in sixty-nine healthy subjects and in twenty-three epileptics on phenobarbitone. The BMCs (and BMDs) of all regions were significantly correlated to each other and to the TBBM (and TBBD). No difference in the ability to discriminate between the different study groups was found for the various regions, excepting the BMD of the head. The relationship between the forearm BMC and TBBM was highly significant, and identical in the five groups. The relationships between spinal BMC and forearm BMC, and TBBM differed in the five groups. It is concluded that some local measurement may be used as estimates of the total body bone mineral in some groups of patients with minor metabolic bone disease and healthy subjects.

Different metabolism of vitamin D2/D3 in epileptic patients treated with phenobarbitone/phenytoin

Serum concentrations of vitamin D metabolites were measured before and during treatment with either vitamin D2 or vitamin D3, 4000 IU per day for 24 weeks, in 22 epileptic outpatients receiving phenobarbitone/phenytoin. The serum concentration of total 1,25(OH)2D did not change during the treatment period in any of the treatment groups. On the other hand, in the vitamin D2 group, serum 25(OH)D2, total 25(OH)D, and 24,25(OH)2D increased significantly during the trial, whereas serum concentrations of the vitamin D3 metabolites were unchanged. In the vitamin D3 group, serum concentrations of the vitamin D3 metabolites increased significantly, whereas the vitamin D3 metabolite levels remained unchanged. However, vitamin D3 treatment resulted in a 2-4-fold greater increase in serum concentrations compared to vitamin D2 treatment. Treatment with vitamin D2 and vitamin D3 in the same dose in IU results in considerably different serum concentrations of the vitamin D metabolites.

Bone mineral content in patients on home parenteral nutrition

Bone mineral content (BMC) was monitored in 15 patients with short bowel syndrome receiving home parenteral nutrition (HPN). Thirteen patients had Crohn's disease and 2 ulcerative colitis (mean age 36 years, range 23-69 years). During the study the patients received HPN for a mean period of 62 months, range 20-106 months. At the time of inclusion the patients had a significantly reduced BMC of lumbar spine and femoral neck compared to normals (Z-scores = -3.35 +/- 3.49, p < 0.05 and Z-score = -2.23 +/- 2.11, p < 0.05). During HPN the Z-score of lumbar spine BMC decreased in 8 patients and increased slightly or was unchanged in 7 patients. The mean Z-score of BMC of lumbar spine declined by 1.46 +/- 2.48 (p < 0.05) and the Z-score of femoral neck BMC declined by 0.831 +/- 1.14 (p < 0.05). This corresponds to a yearly decrease of lumbar spine BMC of 4%. There was no correlation between the decline in BMC during the study and the period of length the patients were on HPN. We conclude that patients on HPN have a low bone mineral density and that the bone loss continues during prolonged HPN.

Relationship between local and total body bone mineral in epileptic patients and normal subjects

Total body bone mineral (TBBM), measured by dual photon absorptiometry, and local body bone mineral content (BMC), measured by single photon absorptiometry, in both forearms were determined in 49 epileptic patients, 19 receiving phenytoin and 30 receiving carbamazepine, and in 55 controls. A highly significant correlation was found between BMC and TBBM in the patients (r = 0.81, SEE = 10.6%), as well as in the controls (r = 0.78, SEE = 9.9%). Furthermore, the intercepts and the slopes were virtually of the same order. The patients on phenytoin had a mild generalised osteomalacia, independent of method used, whereas the patients on carbamazepine did not have this side-effect. It is concluded that BMC of the forearm can be used as a valid estimate of total body bone mineral in groups of epileptic patients and in normal subjects.

Body composition changes measured by dual-energy X-ray absorptiometry in patients receiving home parenteral nutrition

BACKGROUND

To monitor changes in body composition in patients receiving home parenteral nutrition (HPN) and to ascertain whether changes were related to the amount of energy supplied by HPN, we studied prospectively patients with gut failure maintained on HPN.

METHODS

Patients were subjected to repeated measurement of body composition by dual-energy X-ray absorptiometry (DXA), the second investigation being performed after a mean period of 20 (range, 11-26) months. Thirty-two patients were included, one patient was excluded, and five patients died during the study period. At inclusion, the patients had received HPN for a mean period of 30 (range, 6-216) months. The indication for HPN was inflammatory bowel disease (n = 16), abdominal cancers (n = 5), and scleroderma and others (n = 11). The fat-free mass (FFM), fat mass (FM), and total body mineral content (TBMC) were measured by DXA.

RESULTS

Mean body mass index decreased from 21.18 to 20.96 kg/m2 (P = 0.36). The mean FFM showed a small, insignificant increase to 37.68 kg (P = 0.71). Mean TBMC was unchanged at 2.28 kg, and mean FM decreased from 19.25 to 18.17 kg (P = 0.055). During the study period the mean daily energy supply by HPN was reduced from kcal 1195 to kcal 959 (P = 0.004). There was a direct positive correlation between the individual changes in HPN energy supply and body weight and FFM (r = 0.437, r = 0.410, P < 0.05).

CONCLUSION

The body composition of HPN patients was stable, with no change in mean FFM, FM, or TBMC. Individual changes in body weight and FFM correlated with change in HPN energy supply.

Different metabolism of vitamin D2 and vitamin D3 in epileptic patients on carbamazepine

Serum concentrations of vitamin D metabolites were measured in 30 epileptic outpatients on monotherapy with carbamazepine before and during treatment with either vitamin D2 or vitamin D3, 4000 IU per day for 24 weeks. Vitamin D2 treatment increased the serum concentration of 25OHD2, but a corresponding decrease in 25OHD3 resulted in an unchanged serum value of total 25OHD. Vitamin D3 treatment increased the serum concentration of 25OHD3. The resulting serum level of 25OHD was consequently twice the level of that in the D2-treated group. The serum concentrations of the dihydroxy metabolites showed a similar difference between the 2 treatment groups. We conclude that treatment with vitamins D2 and D3 in the same doses produces considerably different serum concentrations of vitamin D metabolites. If the present findings can be extrapolated to normal subjects, it is important to consider more carefully which D-vitamin should be used, both with regard to therapy and supplementation.

Body composition in patients on home parenteral nutrition

Dual energy X-ray absorptiometry (DXA) measures and separates three of the principal compartments of the body, fat mass (FM), fat-free mass (FFM), comprising muscle, inner organs and body water, and the total bone mineral content (TBMC). The aim of the present study was to determine body composition by DXA scan in 37 patients who had been on home parenteral nutrition (HPN) for 6-216 months. The height and weight of patients were significantly lower when compared to a group of healthy subjects. The weight, however, was relatively more reduced than the height. This is reflected by a significantly reduced body mass index in young female and male patients (p < 0.05). Fat-free mass and total body mineral content were significantly reduced (p < 0.05) in patients on home parenteral nutrition compared to a group of healthy subjects. However, the percentage of fat-free mass was unchanged. No significant change in fat mass was observed. We conclude that patients, with intestinal failure due to short bowel syndrome, who are on HPN have a smaller body size with a normal relative body composition.

Effect of 1,25-Dihydroxyvitamin D3 on Biochemical Indices of Bone Turnover in Postmenopausal Women

Bone metabolism was estimated by serum alkaline phosphatase (index of bone formation) and fasting urinary excretions of calcium and hydroxyproline (indices of bone resorption) in a group of early postmenopausal women and a group of 70-year-old women, during 12 months' treatment with 1,25-dihydroxycholecalciferol (1,25(OH)2D3), and compared to oestrogen/gestagen treatment or placebo treatment. The groups treated with 1,25(OH)2D3 did not show any change in bone metabolism, neither in bone resorption nor in bone formation, during the treatment period when compared to the placebo group, whereas treatment with female hormones decreased both bone resorption and bone formation.

Measurement of 25-hydroxyvitamin D3 and 25-hydroxyvitamin D2 in clinical settings

A quick and simple method for the selective measurement of 25-hydroxyvitamin D3 (25OHD3) and 25-hydroxyvitamin D2 (25OHD2) is described. It includes a rapid sample preparation technique and a combination of a selective radioimmunoassay for 25OHD3 and a competitive protein-binding assay using vitamin D-binding protein for the determination of total 25OHD, including 25OHD3 and 25OHD2. The method was compared with a procedure which include methanol/methylene chloride extraction and chromatography on Sephadex LH 20, and a procedure which includes HPLC and final quantification by u. v. detection. The methods were applied to three groups of patients in order to obtain information on how far assay procedures could be simplified for use in the clinical settings. It is concluded that the method described is applicable for following patients on vitamin D2 therapy. When groups of patients have to be compared, the mean values of the estimates are comparable, whether a simple method or a laborious method is used. Hence, the selection of assay method should take into account the clinical problem and the cost of the analysis.

Metabolism of vitamin D2 and vitamin D3 in patients on anticonvulsant therapy

We examined the effect of short-term treatment with pharmacological doses of vitamin D2 or vitamin D3 on the serum concentration of 1,25(OH)2D metabolites in epileptic patients on chronic anticonvulsant drug therapy. Nine patients were studied before and after treatment with vitamin D2 4000 IU daily for 24 weeks and 10 before and after treatment with vitamin D3 in the same dose. Before treatment the serum concentrations of 1,25(OH)2D and 25(OH)D were significantly lower in epileptics than in normal subjects (P less than 0.01). Vitamin D2 treatment increased the serum concentration of 1,25(OH)2D2, but a corresponding decrease in 1,25(OH)2D3 resulted in an unchanged serum concentration of total 1,25(OH)2D. The serum concentration of 25(OH)D2 and 25(OH)D increased significantly, whereas there was a small decrease in 25(OH)D3. Vitamin D3 treatment did not change the serum concentration of 1,25(OH)2D3 whereas serum 25(OH)D3 increased significantly. The correlation between the serum ratio of 1,25(OH)2D2/1,25(OH)2D3 and 25(OH)D2/25(OH)D3 estimated on vitamin D2-treated epileptic patients and normal subjects was highly significant (P less than 0.01). The data indicate that the serum concentration of 1,25(OH)2D2 and 1,25(OH)2D3 are directly proportional to the amount of their precursors 25(OH)D2 and 25(OH)D3 and that the concentration of total 1,25(OH)2D is tightly regulated.

Discrepancy between serum 1,25-dihydroxycholecalciferol measured by radioimmunoassay and cytosol radioreceptor assay

A radioimmunoassay for determination of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) in serum, was compared with the radioreceptor assay using cytosol receptor from rachitic chick intestine in order to clarify whether differences in specificity can explain discrepancies in the clinical application of the two techniques. In the literature, seasonal fluctuations in serum 1,25(OH)2D3 are only observed when using radioimmunoassay. Treatment of anticonvulsant osteomalacia with vitamin D3 results in a marked increase in radioimmunologically measured 1,25(OH)2D3, but no effect on the serum 1,25(OH)2D level, measured by the radioreceptor assay, could be observed. The present study demonstrates that another unknown compound is coeluted on high pressure liquid chromatography with 1,25(OH)2D3, and recognised only by the antiserum. It can be concluded that the present radioimmunoassay cannot replace the cytosol receptor assay or either supplement by measuring the 1,25(OH)2D3 metabolite only.