ASCERTAINING HYPOGLYCORRHACHIA IN AN ACUTE PATIENT

A study was undertaken in an urgent clinical setting to determine whet her the use of a cerebrospinal fluid (CSF) to blood glucose ratio is a ppropriate for describing the relationships between CSF glucose and bl ood glucose in patients who had not fasted. Blood glucose levels were obtained before a lumbar puncture in 79 adults who had normal CSF find ings. Regression analysis of CSF glucose and blood glucose levels of t hese patients who had not fasted, as well as data from four published studies of normal blood and CSF glucose levels, indicated that a ratio was not a valid measure of the normal relationship between CSF and bl ood. Only when the blood glucose level was between 89 and 115 mg/dL wa s the relationship within the expected ''ratio'' of 0.60 to 0.70. In h yperglycemic states, the normal relationship may be substantially lowe r than 0.50. A nomogram is presented which is useful in determining hy poglycorrhachia when the patient is hyperglycemic. Copyright (C) 1997 by W.B. Saunders Company.