Blog entry by Meguid El Nahas

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J Am Soc Nephrol. 2015 Sep 17. pii: ASN.2015010022. [Epub ahead of print]

Urinary Sodium and Potassium Excretion and CKD Progression.

Abstract

CKD is a major risk factor for ESRD, cardiovascular disease, and premature death. Whether dietary sodium and potassium intake affect CKD progression remains unclear. We prospectively studied the association of urinary sodium and potassium excretion with CKD progression and all-cause mortality among 3939 patients with CKD in the Chronic Renal Insufficiency Cohort Study. Urinary sodium and potassium excretion were measured using three 24-hour urine specimens, and CKD progression was defined as incident ESRD or halving of eGFR. During follow-up, 939 CKD progression events and 540 deaths occurred. Compared with the lowest quartile of urinary sodium excretion (<116.8 mmol/24 h), hazard ratios (95% confidence intervals) for the highest quartile of urinary sodium excretion (≥194.6 mmol/24 h) were 1.54 (1.23 to 1.92) for CKD progression, 1.45 (1.08 to 1.95) for all-cause mortality, and 1.43 (1.18 to 1.73) for the composite outcome of CKD progression and all-cause mortality after adjusting for multiple covariates, including baseline eGFR. Additionally, compared with the lowest quartile of urinary potassium excretion (<39.4 mmol/24 h), hazard ratios for the highest quartile of urinary potassium excretion (≥67.1 mmol/24 h) were 1.59 (1.25 to 2.03) for CKD progression, 0.98 (0.71 to 1.35) for all-cause mortality, and 1.42 (1.15 to 1.74) for the composite outcome. These data indicate that high urinary sodium and potassium excretion are associated with increased risk of CKD progression. Clinical trials are warranted to test the effect of sodium and potassium reduction on CKD progression.

COMMENT:

Interesting and not surprising observation linking a high urinary sodium excretion with CKD progression. The association seemd to be affected by the level of albuminuria that also correlated with the rate of CKD progression. 

The authors showed the association to be independent of presence or absence of hypertension, type of anti-hypertensive agent or systolic blood pressure...

BUT...

the association between high urinary sodium excretion, most likely the reflection of high dietary sodium intake, is most liley the refelction of poorly controlled hypertension...

the authors overlook the fact that a casual, occasional, single blood poressure recording is meaningless and doesnt ascertian whether individuals are hypertensive or not and/or controlled or not...

WHEN WILL NEPHROLOGISTS LEARN THAT CASUAL, SINGLE, BP READING DOESNT INFORM ON HYPERTENSION, ITS PRESENCE OR THE QUALITY OF ITS CONTROL...

This whole paper is likely to tell us that a high sodium diet, associated with a high urinary sodium excretion, increases BP, that in turn affects both albuminuria and the rate of CKD progression...no more or less!

 

[ Modified: Thursday, 1 January 1970, 1:00 AM ]

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