Intestinal absorption of cholecalciferol in alcoholic liver disease and primary biliary cirrhosis

The intestinal absorption of (3H)cholecalciferol was studied in five patients with alcoholic liver disease, six patients with primary biliary cirrhosis, and 15 healthy subjects. The rate of appearance in plasma of (3H)cholecalciferol after oral ingestion and the subsequent appearance of (3H) polar metabolites in the alcoholic subjects were similar to those in the healthy subjects. In subjects with primary biliary cirrhosis the rate of appearance in plasma of (3H)cholecalciferol was significantly reduced. The rate of appearance of labelled polar metabolites of cholecalciferol was also lower in this group, suggesting that increased removal of labelled vitamin by conversion into more polar metabolites could not account for the reduced plasma (3H)cholecalciferol response. It is suggested that intestinal absorption of cholecalciferol is usually normal in alcoholic liver disease but impaired in primary biliary cirrhosis. Hepatic 25-hydroxylation is normal in alcoholic liver disease but may be defective in primary biliary cirrhosis.

Changes in ionized calcium and other plasma constituents associated with cardiopulmonary bypass

Plasma concentrations of calcium fractions, proteins, phosphate and magnesium were measured before, during and after cardiopulmonary bypass in 15 patients undergoing cardiac surgery. When calcium chloride was added to a pump priming solution which contained little or no blood, the concentrations of all calcium fractions were significantly greater after bypass than before, with a mean ionized calcium concentration of 1.52 mmol litre-1 plasma water, 30 min after completion of bypass. This iatrogenic hypercalcaemia was increased significantly by the administration of more than 10 mg kg-1 calcium chloride in the first 30 min after bypass. Other plasma constituents showed the dilutional effect of the pump prime during bypass and only the magnesium concentration failed to return towards normal values after operation.

Hepatic osteodystrophy

Hepatic osteodystrophy consists of three types: osteomalacia, osteoporosis, and periosteal reaction with new bone formation. Secondary hyperparathyroidism is very rare, if it occurs at all. The cause of osteomalacia appears to be vitamin D deficiency due to a lack of vitamin D substrate. In the presence of adequate substrates, 25-OHD and dihydroxy vitamin D metabolites are formed. The vitamin D deficiency results in osteomalacia and malabsorption of calcium and phosphorus. The osteomalacia can be treated successfully with vitamin D supplements. In some patients calcium, phosphorus, and magnesium supplements may be required. The aetiology and treatment of the osteoporosis and the periosteal reactions remain obscure.

Phosphate metabolism in chronic liver disease

Phosphate metabolism was investigated in 26 patients with a spectrum of liver diseases and mean fasting plasma phosphate concentrations were in the low normal range. A standard oral load of phosphate was used to test absorption and was subnormal in the majority of patients with large bile-duct obstruction and alcoholic liver disease. Subnormal results were also seen in patients with primary biliary cirrhosis and cirrhosis secondary to chronic active hepatitis. These abnormalities appeared to be related to vitamin-D deficiency. Tubular reabsorption of phosohate was markedly reduced in 3 of 14 patients. The therapeutic implications of phosphate status in liver disease are important.

Formation of vitamin D metabolites from 3H- and 14C-radiolabelled vitamin D-3 in chronic liver diseases

Four of the eight patients studied were vitamin D replete and 4 vitamin D depleted as judged by serum 25-hydroxy vitamin D (25-OHD) concentration. Three of the 4 vitamin D depleted patients (including 2 with histological osteomalacia) formed radioactive 1,25-dihydroxycholecalciferol. One of the four vitamin D replete patients formed 1,25-dihydroxycholecalciferol but all formed 24,25-dihydroxycholecalciferol. This study suggests that patients with liver disease form dihydroxy vitamin D metabolites in an appropriate manner.

Long-term effects of small doses of 1,25-dihydroxycholecalciferol in renal osteodystrophy

An oral dose of 0.5 microgram of 1,25-dihydroxycholecalciferol (1,25-[OH]2D3) and 4 g of calcium carbonate was given daily to two dialysed patients and three undialysed patients in chronic renal failure with renal osteodystrophy. Treatment was given for 4-16 months. Intestinal calcium absorption became normal in all five patients. Plasma alkaline phosphatase, hydroxyproline, and immunoreactive parathyroid hormone were considerably reduced in all of the patients and in four of them these values were restored to normal. Bone histology was improved in all patients after treatment with 1,25-(OH)2D3. As well as a dramatic improvement in bone mineralisation, there was remodeling of trabecular architecture and a decrease in fibrosis in patients with initial parathyroid overactivity.

Plasma calcium and magnesium fractions in liver disease

Plasma calcium and magnesium fractions were measured in 51 patients with either hepatocellular or biliary disease. The fractions were found to be only minimally deranged. Plasma albumin correlated with total calcium and with the protein bound and ionized fractions. Abnormalities of plasma calcium or magnesium fractions are unlikely to play a role in the pathogenesis of the osteomalacia seen in chronic biliary disease.

Serum prolactin in liver disease and its relationship to gynaecomastia

Serum immunoreactive prolactin was measured in 150 patients with liver disease of varying aetiology and severity and in 45 control subjects. The upper limit of the reference range for serum prolactin was 331 mU/l. Eighteen patients with liver disease (12%) had unexplained hyperprolactinaemia. No relationship existed between the prolactin value and the sex of the patient, the aetiology of the liver disease, the severity of the liver disease, or the presence of gynaecomastia. The cause of the hyperprolactinaemia in patients with liver disease and its clinical implications need further investigation.

Clinical, biochemical, and histological studies of osteomalacia, osteoporosis, and parathyroid function in chronic liver disease

Twenty of 32 patients with either chronic cholestatic or hepatocellular liver disease had bone pain or recent fractures. On bone biopsy five patients had normal bone, 15 had osteomalacia, five had osteoporosis, and seven had a combination of osteomalacia and osteoporosis. In the presence of osteoporosis, osteomalacia was minimal or absent. There was no biochemical, radiological, or histological evidence of excess parathyroid activity. No significant correlations were demonstrated between the plasma and urinary biochemical findings and the presence of either osteoporosis or osteomalacia and bone biopsy was essential for correct diagnosis. There was no statistical relationship between low serum 25-hydroxy vitamin D values and the presence of osteomalacia. Bone disease was not prevented by regular intramuscular vitamin D2, although biochemical changes were improved. Drugs such as corticosteroids and cholestyramine may be important aetiological factors in hepatic osteodystrophy.

Parenteral 1,25-dihydroxycholecalciferol in hepatic osteomalacia

Despite regular long-term parenteral vitamin D2 treatment, four patients with biliary cirrhosis had multiple symptoms of bone disease and bone biopsy specimens showed osteomalacia without osteoporosis. Three patients also had a proximal myopathy. Plasma calcium values (after correction for albumin), phosphorus, magnesium, and serum 25-hydroxy-vitamin D were within normal limits. Treatment with 1,25-dihydroxy-cholecalciferol (1,25-(OH)2D3) relieved symptoms in three of the four patients and improved those in the fourth. Histological examination of bone showed improvement in all four patients, but serum and urinary biochemical changes were not pronounced. We conclude that 1,25-(0H)2D3 treatment has a beneficial effect on bone and muscle in hepatic osteomalacia, either because vitamin D 1-hydroxylation fails in biliary cirrhosis or because hepatic osteomalacia is resistant to vitamin D2 metabolites.

Serum 25-hydroxyvitamin D assay. Evalution of chromatographic and non-chromatographic procedures

A competitive protein binding assay for serum 25-hydroxyvitamin D is described in which normal human serum is used as the source of binding protein. A serum sample is extracted with diethyl ether/methanol and then chromatographed using silica gel. Validation of the method is reported. Silica gel chromatography is compared with LH20 chromatography. The method is also compared with extraction techniques using diethyl ether and ethanol without subsequent chromatography. It is concluded that chromatography with either silica gel or LH20 is essential. The non-chromatographic methods investigated, in addition to giving much higher values than chromatographic methods, did not meet validation requirements with respect to accuracy and behaviour of samples on dilution.

Rickets in adult cystic fibrosis with myopathy, pancreatic insufficiency and proximal renal tubular dysfunction

Rickets is reported in a 19 year old white man with cystic fibrosis in whom pancreatic and hepatic involvement was advanced. There was evidence of secondary hyperparathyroidism with proximal renal tubular acidosis, aminoaciduria, phosphaturia and hypophosphatemia. Treatment with oral pancreatic and parenteral vitamin D supplements led to full recovery of the rachitic syndrome and the proximal renal tubular dysfunction.

Seasonal variation in serum-25-hydroxyvitamin-D in the elderly in Britain

In a group of thirty-six non-housebound normal people aged 70 to 88 years living independently in their homes, mean serum-25-hydroxyvitamin-D (+/- 1 S.D.) was 8-62 +/- 3-08 ng/ml in midwinter and had risen to 14-13 +/- 4-90 ng/ml the following September. These values were lower and the seasonal variation was less than previously found in healthy young British adults.

Plasma lipoprotein patterns in patients receiving dialysis therapy for chronic renal failure

A study is reported of the prevalence, nature and possible aetiology of the hyperlipidaemia found in a group of 74 patients receiving maintenance dialysis. Sixty patients were receiving haemodialysis and 14 peritoneal dialysis. Sixty-four per cent of the male and 83% of the female patients had a lipoprotein abnormality which was predominantly of the Type IV pattern, probably due to a combination of increased hepatic triglyceride synthesis and diminished peripheral clearance.

Plasma triglyceride secretion and metabolism in chronic renal failure

Endogenous very low density lipoprotein triglyceride (VLDL-TG) production rate has been studied in 13 patients with chronic renal failure who were not on dialysis treatment. In these patients the VLDL-TG plasma concentration was significanlty raised when compared with the control group; the fractional turnover rate was reduced but the absolute turnover rate was increased. The results suggest that increased hepatic production of VLDL-TG is a contributory factor to the hypertriglyceridaemia of chronic renal failure.

Metabolic response to intravenous salbutamol therapy in acute asthma

In patients suffering from an acute attack of asthma the effects of salbutamol infusion (10 microng/min) on their plasma concentrations of non-esterified fatty acids (NEFA), triglyceride, insulin, and glucose were compared with those in a group of asthmatics not requiring infusion. Salbutamol was found significantly to increase the plasma concentrations of glucose and insulin while having little effect on NEFA or triglyceride. However, NEFA concentrations were found to be significantly increased in patients with an acute attack of asthma at the time of their admission to hospital. This increase is attributed to the stress of the asthmatic attack itself.

The effect of uraemic metabolites on parathyroid extract-induced bone resorption in vitro

A study is reported of the effects of both pre- and post-dialysis serum and some of the known uraemic metabolites on parathyroid extract-induced bone resorption using an in vitro organ culture system. Serum from uraemic patients prior to haemodialysis was shown to inhibit the action of parathyroid hormone on bone and this inhibitory effect was not present after dialysis. Some of the uraemic metabolites studied and also phosphate exerted an inhibitory effect but the metabolites caused their inhibition at higher concentrations than those which are known to occur in uraemic patients. It is concluded that if uraemic metabolites play a role in vivo then it is probably due to a cumulative phenomenon.

Serum-25-hydroxy-vitamin-D in untreated parenchymal and cholestatic liver disease

Serum-25-hydroxy-vitamin-D (25 OHD) concentration has been measured in 106 patients with untreated parenchymal and cholestatic liver disease. Low mean values were found in groups of patients with alcoholic hepatitis and cirrhosis, non-cirrhotic active chronic hepatitis, lupoid and cryptogenic cirrhosis, symptomatic primary biliary cirrhosis, and acute and chronic biliary disease. In a group of patients with presymptomatic biliary cirrhosis the mean value was not significantly different from normal. It is concluded that in the presence of significant parenchymal or cholestatic liver disease serum-25-OHD concentrations are usually low. The mechanisms for the reduction remain to be clarified, but low serum-25-OHD values may play a contributory role in the aetiology of osteomalacia in chronic liver disease.

Persistent hypophosphataemia and osteomalacia in dialysis patients not on oral phosphate-binders: Response to dihydrotachysterol therapy

Four patients who had been on regular haemodialysis for periods of 3 1/2 to 7 years became hypophosphataemic with plasma-phosphate concentrations of 2.5 mg/dl or less before dialysis. None of them had been taking oral phosphate-binders for 2 years or more. Histologically all the patients had an excess of osteoid on bone biopsy. Intestinal absorption of phosphate and calcium was impaired, despite normal or high serum-25-hydroxycholecaliferol concentrations. Treatment with oral dihydrotachysterol resulted in corrections of the phosphate malabsorption and increases in plasma-phosphate concentration. The initial low plasma-phosphate values in these patients before dialysis probably reflected a state of phosphate depletion caused by the combination of malabsorption, loss during dialysis, and a low dietary intake.

Correction of hypocalcaemic symptoms during plasma exchange

The supplementation of replacement solutions used during plasma exchange with calcium gluconate prevents hypocalcaemic symptoms.

Controlled storage of biological energy: The role of plasma lipoproteins

A scheme is advanced whereby plasma-lipoproteins form an integrated controlled pathway for storage of energy as triglyceride. The importance of insulin within this system is indicated and the consequence of possible errors considered. Changes secondary to organ disease are found to fit within the proposed pathway. Although many refinements remain to be added, this hypothesis seems to form a plausible framework within which lipoprotein abnormality and the underlying condition may be better understood and thereby treated.

Muscle weakness in osteomalacia

The muscle weakness that frequently accompanies osteomalacia and rickets may arise from a variety of causes. Particularly in patients with muscle weakness, identification of the metabolic disorder is important, since effective treatment is often possible.

Plasma calcium levels in pregnant Asian women

Plasma calcium, phosphorus, alkaline phosphatase, total protein, and albumin were measured during pregnancy in a group of Asian women living in the south of England and in a control group. The Asian women had slightly lower mean plasma calcium concentrations than the control group. Exposure of Asian women to sunshine appeared to be low, and it was inferred that they probably had little endogenous synthesis of cholecalciferol as a result. Both Asian and control subjects ingested similarly low amounts of vitamin D. The Asian women consumed greater amounts of phytate and vegetable fibres than the controls, and it is suggested that these substances may reduce absorption of insoluble lipids (including cholecalciferol) and calcium in a setting where the dietary intake and endogenous synthesis of vitamin D are already borderline for the subject's requirements.

Disorders of blood-lipids in renal disease

Hyperlipidaemia is a characteristic feature not only of the nephrotic syndrome but also of chronic renal disease without the features of that syndrome. There is evidence for disordered lipid metabolism in patients with chronic renal disease. In these patients the disordered lipid metabolism, the precise cause of which is unknown, is characterised by hypertriglyceridaemia, the aetiology of which is probably multifactorial. Hyperlipidaemia is an important potential risk factor in the aetiology of cardiovascular disease, which may be a leading cause of death in patients undergoing long-term maintenance haemodialysis therapy.

Myopathy in hypophosphataemic osteomalacia presenting in adult life

Three cases of hypophosphataemic osteomalacia presenting in adult life, in which a myopathy was a prominent presenting feature, are described. In one, a nasopharyngeal haemangioma was also present. Possible mechanisms underlying the myopathy are discussed briefly.

Effects of age, sex, and polycystic disease on progressive bone disease of renal failure

A study of 150 patients undergoing haemodialysis has shown that age had a striking effect on the radiological presentation of renal bone disease, erosions being common in the young and uncommon in older patients and vascular calcification showing opposite trends to this. Men aged 20 to 59 years had a greater tendency to develop erosions than did women in this age range. Examination of a group of 53 patients over a period of five years showed that the half time for the development of vascular calcification was 4.6 years, erosions 26.7 years, and fractures 6.9 years. Nine out of 16 polycystic patients matched for age and sex with 50 controls did not develop erosions and had consistently less vascular calcification than the controls when examined over a six-year period.

Long-term variations in serum calcium concentration in normal subjects

In 20 healthy normal Caucasian subjects the serum calcium concentration was measured at three-monthly intervals over two and a half years. There was no evidence of any seasonal variation in serum calcium concentration as a result of variation in endogenous cholecalciferol synthesis.

The relief of bone pain in primary biliary cirrhosis with calcium infusions

Intravenous calcium infusions produced subjective relief of bone pain in 14 patients with primary biliary cirrhosis. The bone pain had developed despite long-term parenteral vitamin D therapy. The pain returned after two to three months, but a subsequent course of infusions again brought relief. Before treatment satisfactory iliac crest bone biopsies were obtained in 11 of the patients and were normal in seven; two patients had biopsies indicating osteomalacia and two osteoporosis. After treatment a repeat biopsy in one of the patients with osteomalacia showed marked reduction in osteoid. The infusion treatment produced no change in plasma calcium concentration, serum phosphate, or serum alkaline phosphatase. Absorption of oral calcium was also unchanged.

Phenytoin inhibition of parathyroid hormone induced bone resorption in vitro

1 A study is reported of the effects of phenytoin and phenobarbitone on bone calcium mobilization by parathyroid hormone in vitro.2 In a therapeutic concentration (15 mug/ml), phenytoin significantly inhibited parathyroid hormone-induced calcium release from bone.3 The inhibitory effect of phenytoin on bone calcium mobilization could play a role in the maintenance of hypocalcaemia in epileptic patients on long-term anticonvulsant drug therapy.

Evolution of bone disease over 10 years in 135 patients with terminal renal failure

An objective radiographic study of erosions, fractures, and periarticular and vascular calcification was made in a series of 135 patients over 10 years of maintenance haemodialysis therapy. The four lesions progressed at different rates, consistent with variation in the response of tissues to a changing biochemical milieu and deficiency in vitamin D metabolites. The half time for development of individual radiographic signs was 3.4 years for vascular calcification, 9 years for fractures, 16 years for periarticular calcification, and 22.9 years for erosions. Calcification of the dorsalis pedis artery seen as a developing ring or tube was an early and valuable sign of disturbed calcium metabolism. In these patients renal osteodystrophy is a chronic condition with a prolonged time course.