Differential Diagnosis for 38F with Schizoaffective Disorder

Given the patient's symptoms of chronic sensation of persistent coldness, dry skin, irregular periods, and normal thyroid function tests (TSH), along with her psychiatric medication regimen, the following differential diagnoses are considered:

• Single Most Likely Diagnosis

  • Hypothyroidism despite normal TSH: Although the TSH levels are within normal limits, some patients can have hypothyroidism with normal TSH levels, especially if they have pituitary or hypothalamic dysfunction. The symptoms of cold intolerance, dry skin, and menstrual irregularities are classic for hypothyroidism. The psychiatric medications, particularly lithium, can affect thyroid function, potentially leading to hypothyroidism.

• Other Likely Diagnoses

  • Lithium-induced hypothyroidism: Lithium is known to cause hypothyroidism in some patients. Even with a normal TSH, the presence of symptoms suggestive of hypothyroidism in a patient on lithium warrants further investigation, including free T4 and free T3 levels.
  • Anemia: Anemia can cause symptoms of cold intolerance and dry skin. Although not directly related to the psychiatric medications, anemia is a common condition that could coexist with the patient's psychiatric condition.
  • Polycystic Ovary Syndrome (PCOS): Irregular periods can be a symptom of PCOS, which is also associated with hormonal imbalances. The presence of dry skin and cold intolerance might be less directly related but could be part of a broader metabolic syndrome.

• Do Not Miss Diagnoses

  • Pituitary Dysfunction: Given the combination of psychiatric medications and symptoms that could suggest endocrine abnormalities, pituitary dysfunction (e.g., hypopituitarism) is a critical diagnosis not to miss. It could explain the normal TSH with symptoms of hypothyroidism, among other hormonal imbalances.
  • Adrenal Insufficiency: Although less likely, adrenal insufficiency can present with a variety of non-specific symptoms, including changes in skin texture and menstrual irregularities. It's a diagnosis that would be critical to identify due to its potential severity.

• Rare Diagnoses

  • Autoimmune Polyendocrinopathy Syndrome: This is a rare condition characterized by the presence of multiple endocrine gland insufficiencies, which could explain the patient's symptoms despite normal TSH levels.
  • Mitochondrial Myopathies: Some mitochondrial disorders can present with endocrinopathies, including hypothyroidism, and other systemic symptoms like cold intolerance. These conditions are rare but could be considered in the differential diagnosis if other explanations are ruled out.