Hyponatremia independent of osteoporosis is associated with fracture occurrence.
OBJECTIVE
Mild hyponatremia has traditionally been considered benign, but it may be associated with gait and attention deficits and an increased risk of falls that may result in fracture. A retrospective study was conducted to quantify the association of hyponatremia with fracture occurrence and to examine whether this relationship is independent of osteoporosis.


METHODS
This study analyzed 1408 consecutive female patients who underwent bone mineral density measurement (Lunar IDXA) between September 1, 2006 and April 11, 2007 and who had available laboratory data. Self reported fracture occurrence was confirmed by radiology report or attendance at a fracture clinic. The significance and independence of the association of hyponatremia with fracture was quantified using logistic regression.


RESULTS
The mean (SD) serum sodium ([Na(+)]) was 140.6 (3.0) mmol/L; 59 (4.2%) had [Na(+)] < 135 mmol/L. Forty-five percent of subjects were osteoporotic and 18% had a prior fracture. Hyponatremia was present in 8.7% of those with versus 3.2% of those without a confirmed fracture (P < 0.001). On multivariate logistic regression analysis controlling for age, T-score, chronic kidney disease stage, osteoporotic risk factors (amenorrhea, family history, regular steroid use, smoking history, alcohol use, history of liver disease, and low-calcium diet), and osteoporosis treatments (calcium and vitamin D supplements, antiresorptives, and hormonal replacement therapy), [Na(+)] < 135 versus [Na(+)] >or= 135 mmol/L remained significantly and independently associated with fracture occurrence (P < 0.01).


CONCLUSIONS
Mild hyponatremia may be a readily identifiable and potentially modifiable risk factor for fracture.
Kinsella
Sinead
S
Department of Nephrology, Cork University Hospital, Cork, Ireland.
Moran
Sarah
S
Sullivan
Miriam O
MO
Molloy
Michael G M
MG
Eustace
Joseph A
JA
D015502:Absorptiometry, Photon; D000058:Accidental Falls; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D015519:Bone Density; D016009:Chi-Square Distribution; D005260:Female; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000209:etiology*; D020233:Gait Disorders, Neurologic / Q000209:etiology*; D006801:Humans; D007010:Hyponatremia / Q000097:blood / Q000150:complications*; D016015:Logistic Models; D008875:Middle Aged; D016017:Odds Ratio; D010024:Osteoporosis / Q000150:complications* / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D012964:Sodium / Q000097:blood; D055815:Young Adult
D015415:Biomarkers; D012964:Sodium