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Normalization of plasma arginine vasopressin concentrations when children with meningitis are given maintenance plus
K R Powell1, L I Sugarman, A E Eskenazi
1Department of Pediatrics, University of Rochester Medical Center, New York 14642.
Insights
In children with meningitis, plasma arginine vasopressin (AVP) levels normalize with adequate fluid and sodium replacement, indicating hypovolemia is the primary driver, not syndrome of inappropriate antidiuretic hormone secretion.
Area of Science:
- Pediatric Endocrinology
- Nephrology
- Infectious Diseases
Background:
- Meningitis in children can lead to complex fluid and electrolyte disturbances.
- Elevated plasma arginine vasopressin (AVP) concentrations are often observed, but their cause (hypovolemia vs. SIADH) is debated.
Purpose of the Study:
- To investigate the relationship between plasma AVP concentrations, hypovolemia, and fluid therapy in children with meningitis.
- To determine if fluid and sodium repletion can normalize elevated AVP levels.
Main Methods:
- A randomized study comparing maintenance fluid plus deficit replacement versus fluid restriction in children with meningitis.
- Measurement of plasma AVP concentrations and serum osmolality before and after 24 hours of fluid therapy.
- Analysis of fluid and sodium intake in relation to AVP changes.
Main Results:
- Children receiving maintenance plus replacement fluids had significantly lower plasma AVP concentrations after 24 hours compared to fluid-restricted children.
- The decrease in AVP concentration correlated with the amount of sodium administered.
- Initial AVP levels were appropriate for hypovolemia, not solely for serum osmolality.
Conclusions:
- Elevated plasma AVP in pediatric meningitis is primarily due to hypovolemia.
- Adequate fluid and sodium administration helps normalize AVP levels.
- Careful monitoring for SIADH is still recommended despite appropriate fluid management.
Abstract:
We hypothesized that plasma arginine vasopressin (AVP) concentrations in children with meningitis are appropriate for the children's degree of hypovolemia, even though the concentrations were higher than expected for the serum osmolality. A randomized study was conducted to compare the effect on plasma AVP concentrations of giving maintenance fluid requirements plus replacement of any deficit versus restricting fluids to two thirds of maintenance requirements for 24 hours. Plasma AVP concentrations and serum osmolality were measured before fluid therapy was begun and again after 24 hours. Nineteen children, 2 months to 17 years of age, were studied; 13 had bacterial meningitis (12 with Haemophilus influenzae type b). Ten children (seven with bacterial meningitis) received a mean of 1.42 times the calculated maintenance fluid requirements, and nine (six with bacterial meningitis) were restricted to a mean of 0.65 times maintenance. Children in the maintenance group also received significantly more sodium (mean = 6.3 mEq/kg/24 hr) than children in the fluid-restricted group (mean = 2.0 mEq/kg/24 hr). The two groups were comparable for plasma AVP concentration and serum osmolality before fluid therapy was begun. The plasma AVP concentration was significantly lower after 24 hours of maintenance plus replacement fluids than after fluid restriction (p = 0.005), and the change in AVP concentration correlated with the amount of sodium given (p less than 0.02). This study supports the hypothesis that serum AVP concentrations are elevated in patients with meningitis because of hypovolemia and become normal when sufficient sodium is given to facilitate reabsorption of water by the proximal tubule of the kidney. Patients with meningitis can be given maintenance plus replacement fluids but should be monitored for the development of the syndrome of inappropriate secretion of antidiuretic hormone.