Role of Dietary Salt Intake in Posttransplant Hypertension With Tacrolimus-Based Immunosuppression G.V.R. Prasad, M. Huang, M.M. Nash, and J.S. Zaltzman ABSTRACT Dietary salt is an important contributor to hypertension in the general population. While its role in cyclosporine-induced hypertension is minimal, its role in tacrolimus-based immunosuppression has not been defined. We measured the 24-hour urine sodium excretion as an estimate of intake in a group of stable renal transplant recipients on tacrolimus (N = 143) who had serum creatinine fluctuations 20% during the preceding 3 months. Average clinic-measured blood pressure (BP) from before and after the 24-hour urine collection was computed. Patients with recent changes in antihypertensive medica- tions were excluded. Average systolic BP was 126  14 and diastolic BP 76  7 mm Hg. Urine sodium was 162.6  70 mmol/d (range 50 to 351), and the sodium/creatinine ratio was 15.4  6.4. There was no correlation between urine sodium excretion and either systolic or diastolic BP (R = 0.07 and R = 0.05, P = NS) or the sodium/creatinine and systolic/diastolic BP (R = 0.13, R = 0.11, P = NS). By multiple linear regression only weight and urine protein were independently associated with both systolic BP (P  .0001 for each) and diastolic BP (P  .05 for each). In conclusion, there is no appreciable influence of dietary salt intake on BP under tacrolimus-based immunosuppression. Restricting dietary salt intake in these patients cannot be recommended at the current time. D IETARY SALT INTAKE is believed to have an important influence on blood pressure in patients with essential hypertension. Salt restriction has been advo- cated as a nonpharmacologic means of treatment. 1 How- ever, hypertension under cyclosporine-based immunosup- pression in renal transplant recipients is believed to be salt independent. 2 The role of salt intake on blood pressure (BP) in patients prescribed tacrolimus has not been defined. METHODS At our center, all patients receive classroom-based counseling on consuming a diet based on DASH guidelines. 3 Patients attending these classes were asked to provide timed 24-hour urine collections for sodium excretion as a surrogate for their dietary intake of this electrolyte. The protein excretion rate and creatinine excretion rates were also measured. Patients were given instructions on the proper collection technique, which includes discarding the first morning urine specimen, and then collecting all subsequent urine through the next 24 hours to and including the next morning’s first specimen in the provided container. Patients were asked to keep the urine refrigerated over this period between individual voids. The serum creatinine value was obtained at the end of the 24-hour period to estimate creatinine clearance. The 24-hour sodium excretion rate was assumed to be equivalent to their dietary intake, with the assumption that they were in a steady metabolic state. Because it is possible that dietary salt intake is at least partly related to body mass, salt excretion was normalized to creatinine excretion as well. Blood pressure measurements in the transplant clinic are per- formed by trained nurses utilizing a calibrated mercury sphygmo- manometer with the patient in an examination room, in the absence of a physician, and in the sitting position. Measurements were performed in accord with the 2000 Canadian guidelines. 4 Both the counseling dietician and nurses measuring blood pressure were blinded to patient participation in the study. Systolic (SBP) and diastolic (DBP) blood pressures from the clinic visit immedi- ately preceding and succeeding the timed 24-hour urine collection were recorded and their arithmetic mean computed. From the Renal Transplant Program, St. Michael’s Hospital, Toronto, Ontario, Canada Address reprint requests to G.V. Ramesh Prasad, MB, BS, MSc, FRCP(C), FACP, Assistant Professor of Medicine, Univer- sity of Toronto, Renal Transplant Program, St. Michael’s Hospi- tal, 61 Queen Street East, 9th Floor, Toronto, ON M5C 2T2 Canada. E-mail: prasadr@smh.toronto.on.ca 0041-1345/05/$–see front matter © 2005 by Elsevier Inc. All rights reserved. doi:10.1016/j.transproceed.2005.04.002 360 Park Avenue South, New York, NY 10010-1710 1896 Transplantation Proceedings, 37, 1896 –1897 (2005)