Clinical and laboratory data of reset osmostat (RO) and cerebral/renal salt wasting (C/RSW) mimic syndrome of inappropriate antidiuretic hormone (SIADH) and can pose diagnostic challenges because of significant overlapping between clinical and laboratory findings. Failure to correctly diagnose hyponatremia may result in increased mortality risk, longer hospital stay, and is cost-effective. We aim to illustrate clinical and laboratory similarities and difference among patients with hyponatremic disorders and discuss the diagnostic value of factional uprate excretion (FEurate) to differentiate SIADH from RO and C/RSW.
We report the use of FEurate in the evaluation of three patients with hyponatremia and elevated urine osmolality in the absence of edema or clinical evidence of dehydration to differentiate SIADH from RO and C/RSW.
Measurement of FEurate may offset in part the diagnostic confusion imparted by the diagnoses of SIADH, RO, and C/RSW.
Research funding: None declared.
Author contributions: All authors contributed equally in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.
Competing interests: The authors declare that they have no relevant financial interests.
Ethical standard: The manuscript does not contain experimental or interventional study.
3. Assadi, F, John, EG. Hypouricemia in neonates with syndrome of inappropriate secretion of antidiuretic hormone. Pediatr Res 1985;19:424–7. https://doi.org/10.1203/00006450-198505000-00003.Search in Google Scholar
4. Maesaka, JK, Imbriano, L, Mattana, J, Gallagher, D, Bade, N, Ahrif, S. Differentiating SIADH from cerebral/renal salt wasting: failure of the volume approach and need for a new approach to hyponatremia. J Clin Med 2014;3:1373–85. https://doi.org/10.3390/jcm3041373.Search in Google Scholar
6. Assadi, F, Agrawal, R, Jocher, C, John, GE, Rosenthal, IM. Hyponatremia secondary to reset osmostat. J Pediatr 1986;108:262–4. https://doi.org/10.1016/s0022-3476(86)81000-9.10.1016/S0022-3476(86)81000-9Search in Google Scholar
7. Saugel, B, Ringmaier, S, Holzapfel, K, Schuster, T, Phillip, V, Scmid, RM, et al.. Physical examination, central venoud pressure, and chest radiography for the prediction of transpulmonary thermodilution-derived hemodynamic parameters in critically ill patients: a prospective trial. J Crit Care 2011;26:402–10. https://doi.org/10.1016/j.jcrc.2010.11.001.Search in Google Scholar PubMed
8. Marik, PE, Cavallazi, R, Vasu, T, Hirani, A. Dynamic changes in arterial waveform derived variables and fluid responsiveness in mechanically ventilated patients: a systemic review of the literature. Crit Care Med 2009;37:2642–7. https://doi.org/10.1097/ccm.0b013e3181a590da.Search in Google Scholar
9. Imbriano, LJ, Ilamathi, E, Ali, NM, Miyawaki, N, Maesaka, JK. Normal fractional uprate excretion identifies hyponatremic patients with reset osmostat. J Nephrol 2012;5:833–8. https://doi.org/10.5301/jn.5000074.Search in Google Scholar PubMed
10. Imbriano, LJ, Mattana, J, Drakakis, J, Maesaka, JK. Identifying different causes of hyponatremia by determining fractional excretion of uric acid. Am J Med Sci 2016. https://doi.org/10.1016/j.amjms.2016.05.35.Search in Google Scholar
12. Welt, LG. Membrane transport defect: the sick cell. Trans Assoc Physicians 1987;80:217–626. PMID: 4330118.Search in Google Scholar
13. Cogan, E, Debieve, MF, Pepersack, T, Abramow, M. Natriuresis and atrial natriuretic factor secretion during inappropriate antidiuresis. Am J Med 1988:409–18. https://doi.org/10.1016/0002-9343(88)90260-4.Search in Google Scholar
14. Maesaka, JK, Imbriano, LJ, Miyawaki, N. High prevalence of renal salt wasting without cerebral disease as cause of hyponatremia in general medical wards. Am J Med Sci 2018;356:15–22. doi:https://doi.org/10.1016/j.amjms.2018.03.020.Search in Google Scholar PubMed
© 2020 Walter de Gruyter GmbH, Berlin/Boston