Primary adrenal insufficiency is a rare condition caused by pathology of the adrenal gland itself, often due to autoimmune adrenalitis or inborn error of steroidogenesis. The adrenal cortex contains three zones, and each zone produces a different hormone - the zona glomerulosa (aldosterone), the zona fasciculata (cortisol), and the zona reticularis (sex steroids). The renin-angiotensin system regulates the production and synthesis of aldosterone, while cortisol is regulated by the hypothalamic-pituitary-adrenal axis. Clinical symptoms depend on whether patient has glucocorticoid and/or mineralocorticoid deficiency, or sometimes androgen deficiency or excess. In patients with glucocorticoid deficiency weakness, weight loss, and anorexia are typically found, while patients with mineralocorticoid deficiency present with hyponatremia, hyperkalemia, acidosis, tachycardia, hypotension, and salt craving. More than 30 different monogenic disorders can cause primary adrenal insufficiency with varying patterns of inheritance. The most common is congenital adrenal hyperplasia due to 21-hydroxylase deficiency. The signs and symptoms of primary adrenal insufficiency might not be specific. Thus, clinicians have a considerable challenge in diagnosing the disease and should have a high index of suspicion. An electrolyte disbalance can provide a clue for diagnosis, but ACTH stimulating test is the most used diagnostic test for adrenal gland dysfunction. As a result of a deficiency in glucocorticoids and mineralocorticoids, the patients require long-term replacement therapy and salt intake as needed. Patients with primary adrenal insufficiency also have androgen deficiency, but the benefits of androgen replacement are less clearly defined, and guidelines do not recommend androgen replacement.