More on renal salt wasting without cerebral disease: response to saline infusion.
OBJECTIVE
The existence and prevalence of cerebral salt wasting (CSW) or the preferred term, renal salt wasting (RSW), and its differentiation from syndrome of inappropriate antidiuretic hormone (SIADH) have been controversial. This controversy stems from overlapping clinical and laboratory findings and an inability to assess the volume status of these patients. The authors report another case of RSW without clinical cerebral disease and contrast it to SIADH.


METHODS
Three patients with hyponatremia, hypouricemia, increased fractional excretion (FE) of urate, urine sodium >20 mmol/L, and concentrated urines were infused with isotonic saline after collection of baseline data.


RESULTS
One patient with RSW had pneumonia without cerebral disease and showed increased plasma aldosterone and FEphosphate, and two patients with SIADH had increased blood volume, low plasma renin and aldosterone, and normal FEphosphate. The patient with RSW responded to isotonic saline by excretion of dilute urines, prompt correction of hyponatremia, and normal water loading test after volume repletion. Hypouricemia and increased FEurate persisted after correction of hyponatremia. Two patients with SIADH failed to dilute their urines and remained hyponatremic during 48 and 110 h of saline infusion.


CONCLUSIONS
The authors demonstrate appropriate stimulation of ADH in RSW. Differences in plasma renin and aldosterone levels and FEphosphate can differentiate RSW from SIADH, as will persistent hypouricemia and increased FEurate after correction of hyponatremia in RSW. FEphosphate was the only contrasting variable at baseline. The authors suggest an approach to treat the hyponatremic patient meeting criteria for SIADH and RSW and changing CSW to the more appropriate term, RSW
Bitew
Solomon
S
Division of Nephrology and Hypertension and Department of Medicine, Winthrop-University Hospital, Mineola, New York, USA.
Imbriano
Louis
L
Miyawaki
Nobuyuki
N
Fishbane
Steven
S
Maesaka
John K
JK
D000368:Aged; D000369:Aged, 80 and over; D000450:Aldosterone / Q000097:blood; D015415:Biomarkers / Q000378:metabolism; D001810:Blood Volume; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000209:etiology* / Q000378:metabolism / Q000628:therapy; D007177:Inappropriate ADH Syndrome / Q000150:complications / Q000175:diagnosis / Q000378:metabolism / Q000628:therapy*; D007262:Infusions, Intravenous; D007552:Isotonic Solutions; D008297:Male; D009994:Osmolar Concentration; D010710:Phosphates / Q000097:blood; D012083:Renin / Q000097:blood; D012964:Sodium / Q000097:blood / Q000652:urine; D012965:Sodium Chloride / Q000008:administration & dosage*; D009626:Terminology as Topic; D013997:Time Factors; D016896:Treatment Outcome; D014527:Uric Acid / Q000097:blood / Q000652:urine; D014883:Water-Electrolyte Imbalance / Q000150:complications / Q000175:diagnosis / Q000378:metabolism / Q000628:therapy*
D015415:Biomarkers; D007552:Isotonic Solutions; D010710:Phosphates; D014527:Uric Acid; D012965:Sodium Chloride; D000450:Aldosterone; D012964:Sodium; D012083:Renin