PROS1 and hyperinsulinemic hypoglycemia, familial, 4: To rule out hepatic dysfunction, nephrotic syndrome, malignancy, and acute-phase reaction as the acquired cause of protein S deficiency; liver function test, urinary albumin creatinine ratio (ACR), serum ferritin, and contrast-enhanced Computed Tomography (CECT) scan (i.e. chest, abdomen, and pelvis) were sent which turned out to be normal.