Nephrol Dial Transplant (2001) 16: 2275-2276
© 2001 European Renal Association-European Dialysis and Transplant Association
Letters and Replies
Intraplatelet calcium levels in patients with acute renal failure
Division of Nephrology and Dialysis, Department of Medicine III, Währinger Gürtel, Vienna, Austria
Sir,
I read with interest the recent publication of Shilliday and Allison on intraplatelet calcium levels in patients with acute renal failure (ARF) [1]. Unfortunately, this article raises more questions than it answers.
- (i) In the abstract, the authors inform the reader that 16 healthy adults and seven patients with ARF were enrolled into the study and that the patients, in double-blind manner, received either torasemide, frusemide, or placebo, 3 mg/kg body weight i.v. every 6 h. In ‘Subjects and Methods’, the reader is informed that five of the patients received a loop diuretic, and two received placebo. Which information is correct?
- (ii) Table 2 shows intracellular calcium in platelets from ARF patients before and after administration of a loop diuretic. Have these data been obtained from five patients on torasemide and five patients on frusemide or five patients either on frusemide or torasemide? Sixteen healthy adult volunteers also received torasemide, frusemide or placebo. There is, however, no information about these data in the manuscript. Is there a decrease of intraplatelet calcium in healthy subjects treated with diuretics (as suggested in the introduction)?
- (iii) We do not have any characterization of the ARF patients and also no laboratory findings. On which days of ARF were the data obtained? When did intracellular calcium rise and was it reversible after recovery from ARF? Were these ARF patients on dialysis treatment?
- (iv) The mean age of the controls was 30 years and that of the ARF patients 60 years. We have recently shown that intracellular calcium in neutrophils increases with age [2]. We do not know whether age also influences intracellular calcium in platelets. However, I would strongly recommend determination of intracellular calcium in platelets in younger and elderly subjects respectively before making the conclusion that ARF per se is responsible for the increase in intracellular calcium in platelets of ARF patients.
- (v) Does intracellular calcium affect platelet function in ARF patients? What are the consequences for ARF patients?
- (ii) Table 2 shows intracellular calcium in platelets from ARF patients before and after administration of a loop diuretic. Have these data been obtained from five patients on torasemide and five patients on frusemide or five patients either on frusemide or torasemide? Sixteen healthy adult volunteers also received torasemide, frusemide or placebo. There is, however, no information about these data in the manuscript. Is there a decrease of intraplatelet calcium in healthy subjects treated with diuretics (as suggested in the introduction)?
References
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Shilliday IR, Allison MEM. Intraplatelet calcium levels in patients with acute renal failure before and after the administration of loop diuretics. Nephrol Dial Transplant2001; 16: 552–555
[Abstract/Free Full Text] - Wenisch C, Patruta S, Daxböck F, Krause R, Hörl WH. Effect of age on human neutrophil function. J Leukoc Biol2000; 67: 40–45[Abstract]
Reply
Renal Unit, Monklands Hospital, Airdrie, UK
Sir,
In reply to Professor Hörl's first question, as indicated in the description of the ARF patients, the seven study patients were part of a larger, double-blind study assessing the effect of loop diuretics on the clinical outcome of ARF. Five of these seven patients were randomized to receive a loop diuretic (three furosemide, two torasemide) and two patients received placebo. The data in Table 2 in the paper was obtained from the patients given the loop diuretic. For the purpose of the study, furosemide and torasemide were combined and defined as loop diuretic. Two patients in the loop diuretic group died before repeat testing approximately 24 h after first administration of loop diuretic.
Professor Hörl is correct, we did not show a decrease in intraplatelet calcium in healthy subjects after the administration of loop diuretics (Table 1
).
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Previous studies have measured intraplatelet calcium in platelets and red blood cells from patients with hypertension.
Intra-platelet calcium levels were measured in ARF patients within 24 h of their presentation, 1 h before administration of loop diuretic or placebo. The second sample was taken approximately 24 h after loop diuretic or placebo were started. The intracellular calcium was raised at presentation; unfortunately we did not remeasure the intra-platelet calcium after recovery from ARF. None of the patients were dialysis dependent at the time the samples were taken, although three did go on to require dialysis. The mean serum creatinine at presentation was 446±185 µmol/l.
We did not study platelet function in our patients with ARF who were given a loop diuretic and hence have no information on Professor Hörl’s interesting final point.
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