Uzu T, Kazembe FS, Ishikawa K, Nakamura S, Inenaga T, Kimura
High sodium sensitivity implicates nocturnal
hypertension in essential 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: