SUMMARY. The seasonal vanation of serum 25-hydroxy vitamin D 3 and 1,25-dihydroxy-vitamin D has been investigated. Blood was taken from 27 healthy volunteers, aged 21-44 years old at 3 monthly intervals over a period of 1 year. A scrolling monthly programme with 12 quarterly (3 month) time periods was developed. A summer associated increase in 25-hydroxy vitamin D 3 was significantly correlated with but lagged behind by 2 months, the increase in recorded sunlight hours. However, four individuals showed no seasonal rise but maintained constant concentrations throughout the year within the established reference range. Serum 1,25-dihydroxy vitamin D showed marked intra-individual variability with no seasonal pattern although the highest concentration (180 pmol/L) was observed in the winter and no concentration greater than 108 pmollL in the summer. Additional key phrases: scrolling 3-month analysis; sunlight assessmentIt is well established that there is a seasonal variation in the serum concentration of 25-hydroxy vitamin D 3 (250HD 3 ) associated with an increase after exposure to sunlight in the summer months and a decrease during the winter months.':" In contrast, there is no seasonal change in the serum concentration of 25-hydroxy vitamin D 2 as it is entirely dietary in origin.1 The effect of seasonal change on serum total 1,25-dihydroxy vitamin D (including D 2 and D 3 ) , the most physiologically active metabolite is less clear since studies using sequential sampling throughout the year the serum 1,25(OH)2D was shown to parallel the serum 250HD 3 concentration-while Chesney et al. I observed no seasonal variation at all.Routine measurement of these compounds is now much easier to carry out because of new improved commercial kits being available. It will be important, therefore, if changes in plasma concentrations of these compounds are to be linked with any pathological defined disease states that misinterpretation is not made because of a normal seasonal variation. The purpose of this investigation therefore was to establish the magnitude of the seasonal variation in the serum

Background: The relationship between cardiac enzyme (CE) release following coronary artery bypass surgery (CABG) and medium term outcome is unclear. We sought to determine the relationship between post-operative CE release and one-year survival following isolated CABG.

SUMMARY.Total serum calcium concentration was raised in a 63-year-old lady with multiple myeloma and markedly elevated serum IgA x-paraprotein concentration. Symptoms of hypercalcaemia were absent, and serum ionized calcium was normal, suggesting calcium binding by the abnormal protein. This was demonstrated directly after isolation of the paraprotein and characterization of the calcium/protein interaction. After reduction of the paraprotein with mercaptoethanol, sodium dodecyl sulphate polyacrylamide gradient gel electrophoresis revealed two bands corresponding to light and heavy chains, but under non-reducing conditions the isolated paraprotein migrated in a series of bands, possibly representing polymeric forms of the basic immunoglobulin moiety. Additional key phrases: ionized calcium; polyacrylamide gradient gel electrophoresis; mercaptoethanol reductionApproximately half the total serum calcium is bound by albumin, with a small proportion complexed by various anionic species. The concentration of free or ionized calcium in the plasma is thought to be the physiologically relevant moiety,' as bound calcium is not immediately available to the tissues. There have been occasional reports of abnormal calcium binding by paraproteins (both IgGs) from patients with m y e l o m a t~s i s ,~-~ in whom total serum calcium was raised, while ionized calcium concentration was normal. Binding of calcium by the myeloma proteins was demonstrated in both cases, and the importance of measuring ionized calcium concentration in patients with myeloma presenting with hypercalcaemia was stressed, in order to avoid vigorous and potentially hazardous treatment for hypercalcaemia.A similar case will be described in whom total serum calcium was raised while the ionized fraction was normal. Isolation of the paraprotein (in this case an IgA) was performed using a combination of affinity chromatography and high performance ion exchange liquid chromatography, and the calcium binding characteristics of the purified IgA examined using equilibrium Correspondence: Dr C J Pearce.dialysis. Further characterization of the paraprotein on polyacrylamide gradient gel electrophoresis (PAGGE) revealed a complex pattern of multiple bands of high molecular weight species, probably representing polymers of the basic 180 kDa immunoglobulin moiety. CASE REPORTMrs S H, a 67-year-old widow, was referred by her general practitioner with a 6 week history of increasingly severe generalized back pain. Radiology of the thoracic and lumbar spine revealed multiple vertebral collapse, and a bone marrow examination showed an excess of plasma cells. Serum albumin concentration was 35 g/L, globulins 73 g/L, and the total serum calcium concentration was 3.5 mmol/L, measured on a SMAC-2 autoanalyser using conventional methodology. Serum immunoelectrophoresis revealed an IgA x-paraprotein. Despite direct questioning there were no symptoms of hypercalcaemia, the Q-T interval on electrocardiography was not shortened, and the serum ionized calcium concentration was within t...

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