Sodium intake and blood pressure in renal transplant recipients

Hypertension is common among renal transplant recipients (RTR) and a risk factor for graft failure and mortality. Sodium intake is a well-established determinant of blood pressure (BP) in the general population. However, data in RTR are limited. International guidelines recommend a maximum daily sodium intake of 70 mmol. We investigated sodium intake in RTR as compared to healthy controls and its association with BP.

We included 660 RTR (age 53 ± 13 years, 58% male) and 201 healthy controls (age 54 ± 11 years, 46% male). Sodium intake was assessed from 24-h urine collections. The morning after completion of urine collection, BP was measured according to a strict protocol.

Urinary sodium excretion was 156 ± 62 mmol/24 h in RTR and 195 ± 75 in controls (difference: P < 0.001), and 95% of RTR had a urinary sodium excretion >70 mmol/24 h. Systolic BP (SBP) and diastolic BP (DBP) were 136 ± 18 and 82 ± 11 mmHg, respectively. Sodium intake was positively associated with SBP (β = 0.042 mmHg/mmol/24 h, P = 0.002) and DBP (β = 0.023 mmHg/mmol/24 h, P = 0.007), independent of potential confounders.

Although RTR had a lower sodium intake than healthy controls, their intake still exceeded current guidelines. Reduction of sodium intake to recommended amounts could reduce SBP by 4-5 mmHg. Better control of sodium intake may help to prevent graft failure and mortality due to hypertension among RTR.