Differential Diagnosis for Unexplained Weight Gain

• Single Most Likely Diagnosis
  • Hypothyroidism: This condition is a common cause of unexplained weight gain due to a decrease in metabolic rate. It is often associated with other symptoms such as fatigue, cold intolerance, and dry skin.
• Other Likely Diagnoses
  • Polycystic Ovary Syndrome (PCOS): PCOS is a hormonal disorder that can lead to weight gain, particularly in the abdominal area. It is often associated with irregular menstrual cycles, acne, and excess hair growth.
  • Cushing's Syndrome: This rare endocrine disorder is caused by excess cortisol production, leading to weight gain, particularly in the abdominal area, as well as other symptoms such as high blood pressure, diabetes, and purple stretch marks.
  • Medication Side Effects: Certain medications, such as steroids, antidepressants, and antipsychotics, can cause weight gain as a side effect.
• Do Not Miss Diagnoses
  • Cushing's Syndrome: Although it is a rare condition, Cushing's Syndrome can be life-threatening if left untreated, making it a crucial diagnosis not to miss.
  • Pheochromocytoma: This rare tumor of the adrenal gland can cause weight gain, as well as other symptoms such as high blood pressure, headaches, and palpitations. If left untreated, it can lead to severe complications.
  • Hypothalamic Tumors: Tumors in the hypothalamus can disrupt normal hunger and satiety signals, leading to weight gain. Early detection and treatment are crucial to prevent long-term complications.
• Rare Diagnoses
  • Prader-Willi Syndrome: This rare genetic disorder is characterized by excessive hunger and weight gain, as well as other symptoms such as short stature, intellectual disability, and behavioral problems.
  • Leptin Deficiency: This rare condition is caused by a deficiency in the hormone leptin, which regulates energy balance and body weight. It can lead to severe obesity and other metabolic problems.
  • Growth Hormone Deficiency: This rare condition can cause weight gain, as well as other symptoms such as fatigue, weakness, and decreased muscle mass.