[19M] Experiencing loss of appetite, constant thirst, and reduced exercise tolerance

Loss of appetite

Differential diagnosis

• Most likely given the symptoms are psychological stress (F43.9), depression (F32.9), and anorexia nervosa (F50.0)
• Less likely but possible are gastrointestinal disorders such as peptic ulcer disease (K25), gastritis (K29.70), and gastroenteritis (K52.9)

Plan

Perform a complete physical examination and mental health screening. Order a complete blood count (CBC), liver function tests, and thyroid function tests to rule out any underlying medical conditions. If symptoms persist, consider referral to a gastroenterologist or psychiatrist for further evaluation.

Excessive thirst

Differential diagnosis

• Most likely given the symptoms are diabetes mellitus (E11.9), diabetes insipidus (E23.2), and psychogenic polydipsia (F98.8)
• Less likely but possible are hypercalcemia (E83.52), chronic kidney disease (N18.9), and Sjogren's syndrome (M35.0)

Plan

Order a fasting blood glucose test and HbA1c to rule out diabetes mellitus. If these tests are normal, consider a water deprivation test to diagnose diabetes insipidus. If symptoms persist, consider referral to an endocrinologist for further evaluation.

Reduced exercise tolerance

Differential diagnosis

• Most likely given the symptoms are anemia (D64.9), hypothyroidism (E03.9), and chronic fatigue syndrome (G93.3)
• Less likely but possible are heart disease (I51.9), lung disease (J98.9), and muscle or joint conditions (M79.1)

Plan

Order a complete blood count (CBC) to rule out anemia, and thyroid function tests to rule out hypothyroidism. If these tests are normal, consider further testing such as an exercise stress test or pulmonary function tests. If symptoms persist, consider referral to a cardiologist or pulmonologist for further evaluation.