PLASMA SPECIFIC-GRAVITY FOR IDENTIFYING HYPOVOLEMIA

To define ranges of plasma specific gravity useful for identifying vol ume depletion in older adults, plasma specific gravity was measured in 170 young adults (mean age 28 years) and 100 retirees (mean age 81 ye ars), and ranges of values likely to be associated with volume depleti on were defined. Subsequently, measurements of plasma specific gravity were made in 68 older emergency room (ER) patients (mean age 74 years ), a few of whom had obvious reasons for being hypovolaemic, e.g. dehy drating diarrhoea, and these results were compared to those for the co ntrol groups. Ranges for plasma specific gravity useful for identifyin g volume depletion were designated as possible hypovolaemia (1.0265-1. 0279), probable hypovolaemia (1.0280-1.0294), definitions, there were more older ER patients compared to both young and old control group su bjects, respectively, with probably hypovolaemia (21% vs. 5% and 8%; p <0.03) and hypovolaemia (16% vs. 0% and 0%; p <0.03). This study esta blishes ranges for plasma specific gravity for young and old adults li kely to be associated with hypovolaemia, and shows that based upon mea surement of plasma specific gravity, older ER patients may often be hy povolemic even in the absence of obvious fluidwasting illnesses. Futur e studies are needed to identify the risk factors for hypovolaemia in ER patients, and more vigorously substantiate the findings of this stu dy.