Decreased Urinary Sodium-to-urinary Creatinine Ratio Identifies Sodium Depletion in Pediatric Acute Gastroenteritis

Abstract

In acute gastroenteritis (AG) fecal losses may cause depletion of sodium (NaD) which may not be recognized because of normal plasma Na (pNa) concentrations. We studied the incidence of this state of normonatremic sodium depletion (NNaD) and the suitability of the urinary Na/urinary creatinine ratio (uNa/uCr) for diagnosing NNaD.

Patients: 16 AG- and 16 healthy control children aged 0.8–15.0 years.

Methods: Prospective cross sectional pilot study. Measurements of Na, K and creatinine in plasma (p) and urine (u). Calculation of uNa/uCr Ratio, fractional excretion of Na (FENa) and uNa/uK ratio as the hitherto best known parameters of prerenal Na depletion, respectively.

Results: pNa concentrations were normal in 15/16 AG patients (93.8%) with only one subnormal value of 133 mmol/L, and a mean value of 137.9±2.3 mmol/L not different from the normal control group (139.4±2.2 mmol/L). Also, mean uNa concentrations and uNa/uK ratios did not differ between both groups. However, uNa/uCr ratios were below normal in 13/16 AG children (81.3%) but normal in all healthy controls with a significantly lower mean value in the AG group (12.6±8.8 vs. 31.2±8.3 mmol/mmol; p<0.0001). Similarly, 14/16 AG patients (87.5%) had a decreased FENa<0.5% with a mean FENa value significantly lower than in controls (0.36±0.28% vs. 0.95±0.26%, p<0.0001). The good agreement between FENa and uNa/uCr results was also reflected by a high correlation coefficient of r=0.9333.

Conclusions: The majority of AG patients was found to have NNaD as determined by uNa/uCr and FENa. Calculation of uNa/uCr may be useful for diagnosing NNaD in AG.

Zusammenfassung

Hintergrund: Bei akuter Gastroenteritis (AG) bleiben Plasma Na (pNa)-Konzentrationen trotz grosser fäkaler Verluste oft normal und reflektieren daher nicht eine tatsächlich bestehende Na-Depletion (NaD). Wir untersuchten die Häufigkeit dieses Zustandes einer normonatriämischen Natriumdepletion (NNaD) und die Bedeutung der Urin-Na/Urin-Creatinin Ratio (uNa/uCr) für ihre Diagnose.

Patienten: 16 AG- und 16 gesunde Kontrollkinder von 0.8 bis 15.0 Jahren.

Methoden: Prospektive Querschnittspilotstudie. Messung von Na, K und Creatinin in Blut und Urin. Berechnung der uNa/uCr Ratio, der fraktionellen Na-Exkretion (FENa) und der uNa/uK Ratio als besten bekannten Parametern prärenal verursachter NaD.

Ergebnisse: pNa-Konzentrationen waren normal in 15/16 AG-Patienten (93.8%) mit nur einem subnormalen Wert von 133 mmol/L, und einem mittleren Wert von 137.9±2.3 mmol/L, welcher sich nicht signifikant von der Kontrollgruppe unterschied (139.4±2.2 mmol/L). Auch die mittlere uNa Konzentration und uNa/uK Ratio zeigten keinen Unterschied der beiden Gruppen. Hingegen war die uNa/uCr Ratio bei 13/16 AG-Patienten (81.3%) subnormal und im Mittel signifikant niedriger war als bei gesunden Kindern (12.6±8.8 vs. 31.2±8.3 mmol/mmol, p<0.0001). Ebenso lag der FENa-Wert bei 14/16 (87.5%) AG-Patienten unter 0.5% und im Mittel signifikant niedriger als bei gesunden Kontrollen (0.36±0.28 vs. 0.95±0.26%, p<0.0001). Die gute Übereinstimmung zwischen uNa/uCr und FENa zeigte sich auch in einem hohen Korrelationskoeffizienten von r=0.9333.

Schlussfolgerung: Ein Großteil der mittels FENa und uNa/uCr Ratio untersuchten AG-Patienten hatte eine NNaD. Die Berechnung der uNa/uCr ist ein nützliches Verfahren zur Diagnose von NNaD bei AG.

Key words

children - acute gastroenteritis - normonatremic sodium depletion - urinesodium-to-urine-creatinine-ratio - fractional sodium excretion

Schlüsselwörter

Kinder - akute Gastroenteritis - normonaträmische depletion - Urinnatrium/Urinkreatinin Ratio - fraktionelle Natriumexkretion

• References

• 1 Adrogue HJ, Madias NE. The challenge of hyponatremia. J Am Soc Nephrol 2012; 23: 1140-1148
• 2 Arieff AI, Ayus JC, Fraser CL. Hyponatremia and death or permanent brain damage in healthy children. BMJ 1992; 304: 1218-1222
• 3 Baylis PH. The syndrome of inappropriate antidiuretic hormone secretion. Int J Biochem Cell Biol 2003; 35: 1495-1499
• 4 Coates AJ, Crofton PM, Marshall T. Evaluation of salt supplementation in CF infants. J Cyst Fibr 2009; 8: 382-385
• 5 Corona G, Guiliani C, Parenti G et al. Moderate hyponatremia is associated with increased risk of mortality: evidence from a meta-analysis. PLOS ONE 2013; 8: e80451
• 6 Edelman IS, Leibman J, O´Meara MP et al. Interrelations between serum sodium concentration, serum osmolarity and total exchangeable sodium, total exchangeable potassium and total body water. J Clin Invest 1958; 37: 1236-1256
• 7 Friedman JN, Goldman RD, Srivastava R et al. Development of a clinical dehydration scale for use in children between 1 and 36 months of age. J Pediatr 2004; 145: 201-207
• 8 Gorelick MH, Shaw KN, Murphy KO. Validity and reliability of clinical signs in the diagnosis of dehydration in children. Pediatrics 1997; 99: E6
• 9 Guandalini S. Acute diarrhea. In: Walker WA, Goulet O, Kleinmann RE, et al. (eds.). Pediatric Gastrointestinal Disease. 2^nd (ed.). BC Decker; 2004
• 10 Molla AM, Rahman M, Sarker SA et al. Stool electrolyte content and purging rates in diarrhea caused by rotavirus, enterotoxigenic E coli and V cholerae in children. J Pediatr 1981; 98: 835-838
• 11 Moritz ML, Ayus JC. Disorders of water metabolism in children: hyponatremia and hypernatremia. Pediatr Rev 2002; 23: 371-380
• 12 Musch W, Hedeshi A, Decaux G. Low sodium excretion in SIADH patients with low diuresis. Nephron Physiol 2004; 96: 11-18
• 13 Neville KA, Verge CF, O´Meara MW et al. High antidiuretic hormone levels and hyponatremia in children with gastroenteritis. Pediatrics 2005; 116: 1401-1407
• 14 Park SJ, Shin JI. Inflammation and hyponatremia: an underrecognized condition. Kor J Pediatr 2013; 56: 519-522
• 15 Reid-Adam J. Hyponatremia. Pediatr Rev 2013; 34: 417-419
• 16 Rodriguez MJ, Alcaraz A, Solana MJ et al. Neurological symptoms in hospitalized patients: do we assess hyponatremia with sufficient care?. Acta Paediatr 2014; 103: e7-e10
• 17 Rossi R, Danzebrink S, Linnenbürger K et al. Assessment of tubular reabsorption of sodium, glucose, phosphate and amino acids based on spot urine samples. Acta Paediatr 1994; 83: 1282-1286
• 18 Sahay M, Sahay R. Hyponatremia: a practical approach. Indian J Endocrinol Metab 2014; 18: 760-771
• 19 Schrier RW. Diagnostic value of urinary sodium, chloride, urea and flow. J Am Soc Nephrol 2011; 22: 1610-1613
• 20 Schrier RW, Sharma S, Shchekochikhin D. Hyponatremia: more than just a marker of disease severity?. Nat Rev Nephrol 2013; 9: 37-50
• 21 Steiner RW. Interpreting the fractional excretion of sodium. Am J Med 1984; 77: 699-702
• 22 Tam RK, Wong H, Plint A et al. Comparison of clinical and biochemical markers of dehydration with the clinical dehydration scale in children: a case comparison trial. Pediatrics 2014; 14: 149-158
• 23 UK Cystic Fibrosis Trust Nutrition Working Group. Nutritional management of Cystic Fibrosis. 2002
• 24 Vega RM, Avner JR. A prospective study of the usefulness of clinical and laboratory parameters for predicting percentage of dehydration in children. Pediatr Emerg Care 1997; 13: 179-182
• 25 Yeates KE, Singer M, Morton AR. Salt and water: a simple approach to hyponatremia. CMAJ 2004; 170: 365-369