HDCN Article Review/Hyperlink

Uzu T, Kazembe FS, Ishikawa K, Nakamura S, Inenaga T, Kimura G

High sodium sensitivity implicates nocturnal hypertension in essential hypertension

Hypertension (Jul) 28:139-142 1996

The clinical importance of sodium sensitivity has not been clearly determined. About 40-50% of essential hypertensives may be salt sensitive, defined in this protocol as a 10% fall in mean MAP (measured using 24 h ambulatory recording) on change from a 12-15 g to 1-3 g NaCl diet.

It is known that some hypertensives lose the normal circadian pattern of BP. This is especially true in patients with renal insufficiency. Kimura's group theorized that the nocturnal non- dipping pattern might be related to salt-sensitivity, as Bigazzi had shown that salt sensitivity was associated with microalbuminuria, and presumably, with glomerular capillary hypertension, whereas others had shown that nocturnal non-dipping was also associated with both microalbuminuria and increased cardiovascular complications.

They studied 28 Japanese patients with EH, and found that sodium sensitive (SS) patients indeed appeared to be nocturnal non- dippers, whether BP was measured on the high or the low salt diet. The nocturnal fall in MAP was positively correlated with the degree of salt-sensitivity. GFR was not measured, but serum creatinine levels and body mass indices were quite similar in the SS and and salt resistnat (SR) patient groups.

Comment: I would have liked to see a comparison of LVH in the two groups. The mechanism whereby salt sensitivity is related to circadian changes in MAP remains speculative. Circadian changes in heart rate were similar in salt-sensitive and salt-resistant patients. The clinical message is, that salt-sensitivity may be associated with a poorer prognosis. (John T. Daugirdas, M.D., University of Illinois at Chicago)

The full text of this abstract is available from the AHA at:
this site .