Salt wasting, hypotension, polydipsia, and hyponatremia and the level of spinal cord injury

Abstract

Case control. To test the reported correlation of hypotension, polydipsia, and hyponatremia with higher levels of spinal cord injury (SCI). A Veterans Administration Hospital, USA. The records of men who were paralyzed owing to trauma at any spinal cord level with motor complete lesions (ASIA A or B) and who received an annual physical and laboratory examination were reviewed for age, duration of paralysis, level of paralysis, blood pressure (BP), serum sodium, and 24 h urinary volume, creatinine, and sodium. Creatinine clearance and fractional excretion of sodium (FcNa) were calculated. Spearman rank-order correlations (r (s)) were carried out. Patients were aged 25 to 88 years, median 56 years, paralyzed 2-61 years, median 26 years, with levels of paralysis ranging from C2 to L4, median T4, n=111. From lower to higher levels of paralysis FcNa increased (0.4-7.3%), mean BP diminished (132-66 mmHg), urine volume increased (600-5400 ml), and serum sodium was reduced (148-129 mEq/l) - r (s)=0.29, 0.49, -0.22, and 0.23, respectively. Increasing 24 h urinary volumes correlated with lower serum sodium concentrations but higher creatinine clearance, r (s)=-0.28, 0.24. Increasing 24 h urinary sodium improved creatinine clearance, r (s)=0.37. P-values ranged from <0.05 to <0.001. Higher levels of SCI correlate with reduced sodium conservation, hypotension, polydipsia, and hyponatremia. Greater water intake raises creatinine clearance but lowers serum sodium. Greater salt intake increases creatinine clearance.