Age and gender as risk factors for hyponatremia and hypernatremia.
BACKGROUND
This study assesses gender and age as independent risk factors for hypo- and hypernatremia and describes the prevalence of hypo- and hypernatremia in different population groups.


METHODS
Details of all serum Na results with accompanying patient demographics for 2 years were downloaded from the laboratory database into Microsoft Access for multiple logistic regression analysis using SPSS. Female gender and age <30 years were the reference groups.


RESULTS
Data from 303577 samples on 120137 patients were available for analysis. Prevalence at initial presentation to a health care provider of Na<136, <116, >145, and >165 mmol/l were for acute hospital care patients: 28.2%, 0.49%, 1.43%, and 0.06%; ambulatory hospital care: 21%, 0.17%, 0.53%, and 0.01%; community care: 7.2%, 0.03%, 0.72%, and <0.01%. Age odds ratios rose with increasing age to 1.89 and 8.70 (Na<136 and <116 mmol/l) and 7.09 and 24.39 (Na>145 and >165 mmol/l, respectively) for age >81 years. Male gender was a mild risk factor for Na<136 mmol/l and was otherwise unimportant.


CONCLUSIONS
Hyponatremia is a common but generally mild condition while hypernatremia is uncommon. Increasing age is a strong independent risk factor for both hypo- and hypernatremia. Gender is not an important risk factor for disturbances of serum Na concentration.
Hawkins
Robert C
RC
Department of Pathology and Laboratory Medicine, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore 308433, Singapore. Robert_Hawkins@ttsh.com.sg
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D006955:Hypernatremia / Q000453:epidemiology*; D007010:Hyponatremia / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012737:Sex Factors; D012846:Singapore / Q000453:epidemiology; D012964:Sodium / Q000097:blood
D012964:Sodium