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A 91 year old lady on a geriatric ward. Serum results are Sodium: 144 mmol/L Potassium: 4.6 mmol/L Urea: 9.4 mmol/L (2.8 - 7.0) Creatinine: 143 umol/L (62 - 133) Albumin: 33 g/L (35 - 49) Adjusted calcium: 2.46 mmol/L 2.10 - 2.55) Intact parathyroid hormone: 13.7 pmol/L (1.1 - 7.6) Clinical information given is 'high calcium'. Results two weeks previously were Sodium: 145 mmol/L Potassium: 5.2 mmol/L Urea: 15.9 mmol/L Creatinine: 123 umol/L Albumin: 32 g/L Adjusted calcium: 2.68 mmol/L. This Case attracted 32 participants. 11 would contact the Physician, [1.0] 4 enquiring about drug use, [1.0] and 4 enquiring about food and hydration status. [1.5] 3 asked why this PTH had been measured. [1.3] 6 thought that the first high calcium was likely to be associated with dehydration; [1.0] 2 thought the results from the previous sample were likely to be artefactual. [-0.5] 4 thought the results suggested hyperparathyroidism; [0.6] 3 commented on the difficulty of interpretation of this PTH value. [1.5] 6 thought that the results suggested primary hyperparathyroidism; [0.8] 4 suggested (co-existing) Vitamin D deficiency; [0.3] 3 suggested secondary hyperparathyroidism; [-0.3] 2 each suggested renal dysfunction; [-0.3] malignancy; [0.3] tertiary hyperparathyroidism. [-0.8] 12 would repeat the serum calcium; [0.8] 3 of these would also measure phosphate; [0.8] 3 would also measure PTH; [0.3] 2 would also measure alkaline phosphatase; [0.8] 1 would also measure magnesium [0.5] 3 would carry out serum protein electrophoresis; [0.5*] 2 would measure (25-OH) Vitamin D; [0.5] 1 would also measure 1,25-OH Vitamin D. [0.0] 2 would ask for a 24 hour urine for calcium. [0.0] 1 suggested skull and hand x-ray; [0.0] 1 suggested assessment for kidney stones. [-0.8] I had considerable difficulty in commenting on this Case, because first, I do not know what happens to serum PTH in extreme age (I know it is likely to rise after an abrupt fall in calcium); and second, I am always wary about suggesting considerable further investigation in very old patients unless there is a clear clinical need for this. My comment was 'Now normocalcaemic. PTH may be slightly raised relative to current calcium; but was previous high calcium associated with dehydration? Possibly secondary hyperparathyroidism related to mild renal impairment or to Vitamin D deficiency.' We have had no further samples from this patient, so I do not know the current clinical position. In response to those who queried the wisdom of measuring PTH on this sample, I to some extent agree. A year ago, in my own Department we would have waited to see what the current calcium was before deciding whether to proceed to a PTH. With ever-increasing pressure to improve turn-round times (and, I hate to add, reduce the number of decision-making processes involved in analysis), we currently do not do this. Right or wrong? Best wishes to all - Case 51 should appear in around three weeks. We will try and produce the overview of Cases 26 - 50 tomorrow. Best wishes Gordon Challand %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%