Thanks to Jacquie Osypiw for suggesting this Case.
A 53 year old lady, seeing her Family Doctor. Clinical information is
'Delicate electrolyte balance. On warfarin'.
Serum results are
Sodium: 140 mmol/L (135-145)
Potassium: 4.6 mmol/L (3.5 - 5.3)
Bicarbonate: 20 mmol/L (22-31)
Urea: 8.2 mmol/L (2.8 - 7.0)
Creatinine: 122 umol/L (62 - 133)
Albumin: 38 g/L (35 - 49)
Adjusted calcium: 2.32 mmol/L (2.10 - 2.55)
Magnesium: 0.47 mmol/L (0.70 - 1.00)
Phosphate: 1.57 mmol/L (0.81 - 1.45)
Uric acid: 428 umol/L (149 - 446)
This Case attracted 29 participants.
11 of these would contact the GP to discuss the Case or to obtain a drug
history. [1.3]
2 would make no comment. [-1.0]
10 mentioned the low magnesium, [1.3]
4 querying renal loss; [1.3]
2 querying GI loss. [1.3]
8 queried diuretic use, [0.7]
4 queried the presence of diarrhoea, [1.0]
4 queried laxative abuse, [0.7]
2 queried renal tubular acidosis [0.3]
1 adding 'secondary to analgesic abuse', [-0.3]
3 mentioned mild renal impairment, [0.3]
1 mentioned dehydration, [0.3]
2 queried whether the patient had been on TPN, [-0.7]
3 queried alcoholism, [1.0]
1 queried Crohn's disease. [-0.3]
4 stated the patient needed magnesium replacement, [1.0]
3 would measure LFTs, [0.3]
2 each would
ask for a repeat sample to check electrolytes, [1.0]
ask for a 24 hour urine magnesium collection, [0.3]
1 adding calcium, phosphate and urea to this measurement, [0.5]
1 each would measure/ suggest measuring
fasting blood glucose, [-0.3]
samples to exclude myeloma, [-1.0]
PTH, [-1.0]
24 hour urine catecholamines, [-0.7]
alcohol, [0.3]
chloride, [0.7]
urine laxative screen [0.7]
creatinine clearance, [1.0]
thyroid function tests. [0.0]
Jacquie was concerned about the low magnesium, and saw that a sample from
two weeks earlier had a magnesium of 0.63 mmol/L, and four weeks before
that was 0.68 mmol/L. She telephoned the Family Doctor, who explained that
he was monitoring the patient on behalf of a Consultant at another hospital
in London. The patient had had radiotherapy previously for an abdominal
malignancy, and had small loop bowel syndrome together with some renal
impairment. She was receiving magnesium and bicarbonate supplements, but on
the basis of these results the magnesium needed to be increased.
Jacquie's comment was simply 'note very low magnesium, levels have been
falling'.
Three weeks later, the serum magnesium was 0.81 mmol/L.
I am away next week, so the Summary to Case 75, and Case 76 the last of the
old Millennium) will be circulated in the week beginning December 6th.
Best wishes
Gordon Challand
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