Prolonged vitamin D intoxication: presentation, pathogenesis and progress.

Vitamin D toxicity from unactivated vitamin D (calciferol) therapy is currently a rare cause of hypercalcaemia. However, the frequency of this event may increase as high-dose unactivated vitamin D preparations become available. Prolonged vitamin D toxicity can cause reversible hypercalcaemia and partially reversible renal impairment. Parathyroid hormone may not be suppressed with unactivated vitamin D toxicity, especially if renal disease coexists.

The adenylate cyclase activity of isolated hepatocytes actions of glucagon and sodium fluoride.

Isolated hepatocytes converted exogenous [alpha-32P]ATP to cyclic [32P]AMP at high rates. This system was used for kinetic studies of the effects of glucagon, fluoride, free magnesium and free ATP4- on adenylate cyclase. In the absence or presence of glucagon, free Mg2+ activated adenylate cyclase by decreasing the Km for MgATP2- without changing V. Free ATP4- was not a potent inhibitor of adenylate cyclase and the only effect of glucagon was to increase V. Fluoride also increased the V of adenylate cyclase, but, in contrast to the results obtained with glucagon, the effect increased as the concentration of free Mg2+ increased. One explanation of the effect of fluoride, consistent with the idea that free Mg2+ activates adenylate cyclase and free ATP is not an inhibitor, is that fluoride increases the affinity of the enzyme for Mg2+. Weak inhibition of adenylate cyclase by ATP4- in the presence of fluoride cannot be excluded.

Formation of cyclic AMP from exogenous ATP by isolated hepatocytes and adipocytes.

Suspensions of isolated rat hepatocytes and adipocytes converted exogenous ATP to cyclic AMP at a rate which was about 30--50% of that observed with homogenates of isolated cells. Formation of cyclic AMP was stimulated by hormones (isoprenaline in the case of adipose tissue and glucagon in the case of liver) and sodium fluoride. Experiments with [alpha-32P]ATP indicated that the conversion of exogenous ATP to cyclic AMP did not occur within the cells. It is proposed that in isolated hepatocytes ad adipocytes some catalytic units of adenylate cyclase are exposed on the outer surface of the cell membrane.

Serum creatine kinase levels parallel the clinical course for rhabdomyomatous Wilms tumor.

A right-sided renal mass in an 11-month-old girl was diagnosed by percutaneous needle biopsy as Wilms tumor, which on histologic examination was found to be predominantly rhabdomyomatous. As part of the examination, serum creatine kinase (CK) and CK-MB levels were measured and were significantly elevated at 994 U/L (reference range, 42-180 U/L) and 40 U/L (reference range, 0-3 U/L), respectively. Subsequently, an 8-month-old girl was admitted to the hospital with septicemia and was found to have an abdominal mass. A diagnosis of bilateral Wilms tumor was made following percutaneous biopsy of both kidneys; histologic examination confirmed that the tumor was predominantly rhabdomyomatous. Serum CK and CK-MB levels also were measured and were significantly elevated at 685 U/L and 84.4 U/L, respectively. In both cases, the serum CK and CK-MB levels reflected the clinical course; elevation in serum levels was associated with tumor recurrence, infarction, or chemotherapy-related necrosis. We conclude that these enzymes have clinical usefulness as markers for Wilms tumor showing rhabdomyomatous morphologic features.

Disturbances of calcium and magnesium metabolism occur in most hyperthyroid patients.

The concentrations in serum of total and ionised calcium, phosphate, magnesium, albumin and alkaline phosphatase activity were measured in patients when hyperthyroid and again when euthyroid. Significant declines in the mean values of ionised calcium, phosphate and alkaline phosphatase activity and significant increases in the mean concentrations of magnesium and albumin were observed. Similar changes were observed in most individual patients. Levels of ionised calcium greater than two standard deviations (representing between batch imprecision) above the upper limit of the reference range were present in 15.6% of hyperthyroid patients. The hyperthyroid levels of calcium, ionised calcium and alkaline phosphatase activity were highest in patients with the most severe thyrotoxicosis. Disturbances of calcium and magnesium metabolism are frequent in hyperthyroid patients.

Effects of sodium dodecylsulphate, dye concentration and paraprotein on coomassie blue dye-binding assays for protein in urine.

Various Coomassie Blue reagents, containing either increased dye concentration or added sodium dodecylsulphate, were compared with a biuret method for the assay of total protein in urine. When immunoglobulin free light chain protein or immunoglobulin paraprotein were present, results from the Coomassie Blue methods were up to 50% lower than with the biuret method; increased dye concentration did not improve comparability substantially, but the addition of sodium dodecylsulphate reduced the bias to about 20%. When neither free light chain protein nor immunoglobulin paraprotein was present, results from the Coomassie Blue methods were only about 30% lower. The addition of sodium dodecylsulphate reduced this bias to 10%. Correlations between the biuret and the Coomassie Blue method were best when the Coomassie Blue reagent contained 40 mg/L sodium dodecylsulphate (r better than 0.98 in all groups; p less than 0.001).

Hemoglobin A1 and serum fructosamine levels in hyperthyroidism.

The severity, prevalence and pathogenesis of abnormalities of carbohydrate metabolism in hyperthyroidism are incompletely defined. The extent of glycosylation of proteins provides an objective, retrospective index of glycemic control. We have measured the percent hemoglobin A1, random plasma glucose level and serum concentrations of fructosamine, total protein and albumin in hyperthyroid and euthyroid subjects attending a hospital-based thyroid clinic. A significant (p = 0.002) increase in the mean value for hemoglobin A1 and a significant (p = 0.0003) decrease in the mean values for fructosamine were found in the hyperthyroid group. The lower mean fructosamine value in the hyperthyroid group was attributed to a concomitant decline in the mean albumin concentration (p = 0.001). The mean value for glucose tended to be higher in the hyperthyroid group, but the difference did not reach significance at the 0.05 level (p = 0.09). The finding of a higher mean hemoglobin A1 concentration in hyperthyroid patients compared to euthyroid subjects is new evidence for a persistent abnormality in glycemic regulation in most thyrotoxic patients.

A method for the separation of delta bilirubin using Cibacron Blue affinity chromatography.

We developed and evaluated a method for the separation of delta bilirubin (B delta) by micro-column affinity chromatography based on Cibacron Blue 3G-A-Agarose. Untreated serum was applied to affinity columns and free non-protein bound bilirubins were eluted with phosphate buffer containing 20 g/l Triton X-100. Retained albumin was eluted using caffeine-benzoate reagent and bilirubin associated with this fraction (B delta) quantitated by the method of Jendrassik and Gróf modified by Doumas et al (Clin Chem 1985;31:1779-1789); results correlated well with the high performance liquid chromatography (HPLC) method (n = 35, y (affinity) = 1.009x (HPLC)-5.49; r = 0.959) described by Lauff et al. (J Chromatography 1981;226:391-402). Two controls analyzed with each batch gave between-batch imprecision less than 4.0% (n = 10; Control 1, mean = 20.05 mumol/l; Control 2, mean = 74.82 mumol/l). Within-batch imprecision was less than 3.3% for both levels. Specimens collected from 25 neonates less than 20 days of age showed a B delta concentration of 1.7 +/- 0.7 mumol/l (mean +/- 1 S.D.) and percent B delta of 2.2 +/- 1.9 (mean total bilirubin +/- 1 S.D. = 118 +/- 79 mumol/l). Although time consuming, this simple and precise method allows the measurement of B delta in laboratories without the need for specialized instruments.

Comparison of urinary albumin excretion between Maoris, Pacific Island Polynesians and Europeans with non-insulin-dependent diabetes.

Elevated urinary albumin excretion is a marker for increased mortality and morbidity in European subjects with non-insulin-dependent diabetes. Urinary albumin excretion was compared in 32 Maoris, 34 Pacific Island Polynesians and 66 subjects of European origin with non-insulin-dependent diabetes attending a diabetes clinic in Wellington, New Zealand. The random urinary albumin to creatinine ratio was used as an estimation of urinary albumin excretion rate. The random urinary albumin to creatinine ratio was significantly higher in Maori and Pacific Island Polynesian subjects, compared to diabetic Europeans (geometric mean urinary albumin to creatinine ratios were 13.13, 12.00 and 2.79 mg/mmol respectively, P less than 0.05). These findings would be consistent with the high mortality and morbidity seen in the Maori and Pacific Island Polynesian diabetic populations. The correlation between hypertension and increased urinary albumin excretion was stronger in the Europeans than in the Maoris and Pacific Island Polynesians studied, suggesting that differences in blood pressure alone are unlikely to account for the observed differences in albumin excretion. Follow-up studies are required to determine whether diabetic Maoris and Pacific Island Polynesians with increased urinary albumin excretion have a similar prognosis to their European counterparts.

The prognostic significance of urinary albumin in Polynesians with non-insulin-dependent diabetes.

Polynesian (59 Maori and 30 Pacific Island) patients were identified from two diabetes clinic registers and followed for a mean of 4.8 years, in order to determine the prognostic significance of urinary albumin excretion. Events were defined as death or entry onto a renal replacement programme. Fourteen events occurred during the period of follow-up. Urinary albumin/creatinine ratio was treated as a continuous variable in a proportional hazards analysis. A 10-fold increase in albumin/creatinine ratio was associated with a 5-fold increase in the risk of an event (95% C.I. = 2.05-12.09). In conclusion, elevated urinary albumin/creatinine predicted mortality and renal morbidity in Maori and Pacific Island patients with non-insulin-dependent diabetes.

Effects of low and high relative molecular protein mass on four methods for total protein determination in urine.

Four commonly used methods for the determination of total protein in urine were compared. These were two biuret methods using different precipitants, a Ponceau S method and a Coomassie Brilliant Blue method. The protein content of the urines was also evaluated by sodium dodecylsulphate polyacrylamide gel electrophoresis. The biuret method with ethanolic phosphotungstic acid as precipitant correlated best with the Coomassie Brilliant Blue method (r = 0.944; p less than 0.001) but less well with the Ponceau S (r = 0.895; p less than 0.001) or biuret-trichloroacetic acid (r = 0.874; p less than 0.001) methods. For urines with normal electrophoretic protein patterns, the imprecise biuret-trichloroacetic acid method (cv = 18.5%) gave the greatest number of false high results (23 in 36 urines) as assessed by electrophoresis. False low results were common in low relative molecular mass (Mr) proteinuria, especially with the biuret-tricholoroacetic acid and Ponceau S methods. High Mr proteinuria rarely caused false low results. Discrepancies between methods appear to have resulted from incomplete precipitation of low Mr protein by trichloroacetic acid.

Clinical and ethnic characteristics associated with urinary albumin excretion in noninsulin dependent diabetic subjects attending the Wellington Hospital diabetes clinic.

In noninsulin dependent diabetes, elevation of urinary albumin excretion above the normal range is thought to predict increased mortality. A random urinary albumin/creatinine ratio and the following clinical characteristics were recorded on 405 patients with noninsulin dependent diabetes attending the Wellington Hospital diabetes clinic; (1) ethnic origin, (2) age, (3) sex, (4) age at diagnosis, (5) duration since diagnosis of diabetes, (6) body mass index, (7) systolic blood pressure, (8) diastolic blood pressure, (9) retinopathy, (10) insulin therapy, (11) antihypertensive therapy, and (12) the presence or absence of treated cardiovascular disease. The overall prevalence of elevated urinary albumin/creatinine ratio (greater than 2.2 mg/mmol) was 45%. Stepwise regression analysis showed that 12% of the variability of urinary albumin/creatinine ratio in our clinic population could be accounted for by ethnic origin of patients, with noncaucasians (the Maori, Pacific Islanders and Asians) having a higher urinary albumin excretion than caucasians (p less than 0.001). Systolic blood pressure, retinopathy and cardiovascular disease predicted a further 8% of this variability. The cause of this ethnic difference in urinary albumin excretion and its possible relationship to excess mortality in noncaucasians is not yet known.

A study of L-thyroxine replacement.

We studied consecutive requests for in vitro thyroid function tests on patients receiving L-thyroxine (T4) for primary hypothyroidism for a three month period May to July 1990, and waited a further three months before ascertaining any changes made to the daily dose of T4. Serum sensitive TSH (sTSH) concentrations were normalised in only 43% of patients treated by a hospital general physician, 50% of patients treated by a specialist endocrinologist and 52% of patients treated by their primary care physician. The respective figures for elevated serum sTSH concentrations were 43%, 33% and 32% and for suppressed levels 15%, 17% and 15%. The dose of T4 required to normalise serum sTSH levels was approximately 110 micrograms/d. In 36% of those patients with suppressed serum sTSH levels the daily dose of thyroxine was reduced. This achieved a mean reduction in the daily dose of 20 micrograms. In 30% of those with raised serum sTSH levels the daily dose of thyroxine was increased. This achieved a mean increase in the daily dose of 15 micrograms. Patients receiving T4 may have raised serum free T4 (fT4) despite normal sTSH levels indicating that serum fT4 measurement is not the test of choice for screening for adequacy of T4 replacement.

Serum enzymes in hypothyroidism.

AIM: To report three cases of hypothyroidism detected because of unexplained elevation of serum enzyme levels on biochemical testing. METHODS: Clinical details and serum enzyme results were obtained before and after L-thyroxine (T4) replacement therapy. RESULTS: The three patients all had serum creatine kinase (CK) levels > 2000 U/L, aspartate aminotransferase (AST) > 90 U/L, and lactate dehydrogenase (LD) > 300 U/L at presentation, with these levels being 10-15, 2-6, and 2-3 times the upper reference limits respectively. CK isoenzyme determination was consistent with skeletal muscle origin. Thyroid function tests performed after consultation with the clinical biochemist confirmed the biochemical diagnosis of primary hypothyroidism. A rapid fall toward normal serum enzyme levels occurred in response to T4 replacement therapy. CONCLUSIONS: Although serum enzymes are an integral part of both the liver and cardiac profiles provided by laboratory, they are not organ specific, and changes may reflect dysfunction elsewhere in the body. Elevations of serum CK (and other muscle enzymes) may occur in hypothyroid subjects, the cause of which has not been established. The clinical diagnosis of hypothyroidism requires a high index of suspicion and should be considered in patients with unexplained persistent elevations of serum muscle enzymes.