Pseudohypoaldosteronism (PHA) is due to end organ resistance to mineralocorticoids. It is usually inherited in an autosomal recessive or autosomal dominant pattern, and rarely can a result of the mutation de novo. Zennaro MC, Hubert EL, Fernandes-Rosa FL. Aldosterone resistance: structural and functional considerations and new perspectives. Mol Cell Endocrinol. 2012;350:206-15.10.1016/j.mce.2011.04.023[Crossref], [PubMed], [Web of Science ®] It can be sub-classified into two forms PHA type 1 A involving the kidneys or PHA-1 B which effects multiple organs. PHA type 2 (Gordon syndrome) presents with hyperkalemia and hypertension. Case: Our patient is a 5 week old male who admitted for significant electrolyte abnormalities. He was followed by PCP for failure to thrive. The child was referred to ED with increased difficulty in feeding, lethargy and episodes of emesis. In the ED, the child was in a compensated shock and had a low normal BP: 76/35, HR: 169/min and fast breathing R/R: 80/minute and afebrile. P.E: showed signs of dehydration. Lab work showed: Na: 110 mEq/L, K: 9.3 mEq/L, low Chloride and Ca: 11.1 mEq/L. Endocrinology recommended IVF supplementation with 2 x NS bolus followed by IVF’s at 1.5 times maintenance (D5 + NS), along with administration of Florinef 0.2 mg suspecting CAH. Renin, 17-OHP, random cortisol level and thyroid hormone levels were ordered. Results showed: TSH of 5.30 mcIU/mL and Free T4 of 2.2 ng/dL. Cortisol: 20.5 mcg/dL. He was subsequently admitted to PICU. Septic work-up was negative. He became hemodynamically stable after hydration and did not require the stress dose of hydrocortisone. Repeat Na: 133 mEq/L, K: 4.7 mEq/L, Cl: 102 mEq/L and Glucose: 90 mg/dL. ACTH stimulation test for CAH evaluation was performed, stimulated 17OHP: 88 ng/dl, cortisol: 27.1 mcg/d and normal DOC. Elevated Aldosterone: 632 ng/dl (5-80) and renin level: 351 (6.5-86). A diagnosis of PHA was made and florinef was stopped and the child was started on NaCl supplementation which normalized the electrolytes. Genetic testing was negative for NR3C2, CUL3, KLHL3, SCNN1A, SCNN1B, SCNN1G, WNK4 and showed that the patient is a heterozygous for a variant of unknown significance, c.6276T>A (p.Ser2092Arg) in the WNK1 gene. However, the patient did not have hypertension and urine electrolytes were also normal did not show signs of PHA 2. Conclusion: PHA can present with severe salt wasting crisis. It can be diagnosed clinically. The relationship of mutation and phenotype can be elusive. Course was uncomplicated and he was discharged from the PICU in 6 days. Sodium doses were titrated based on serum levels with eventual dose of 22.5mEq/kg/day and sodium level was 139 mEq/L.