CTLA4 and Hyponatremia: More recently, Seethapathy et al. showed that only 0.3% of severe hyponatremia were due to endocrinopathies and that the risk factors for developing severe hyponatremia were the use of anti-CTLA-4 monotherapy compared to anti-PD-1, use of diuretics, and cirrhosis, and non-White race (70).