Differential Diagnosis for Persistent Fatigue, Unexplained Weight Gain, Difficulty in Concentrating, Puffiness around Eyes, and No Palpable Thyroid Nodules or Enlargement

Single Most Likely Diagnosis

• Hypothyroidism: This condition is characterized by a decrease in thyroid hormone production, which can lead to symptoms such as fatigue, weight gain, difficulty concentrating, and puffiness around the eyes. The absence of palpable thyroid nodules or enlargement does not rule out hypothyroidism, as it can occur without these physical findings.

Other Likely Diagnoses

• Polycystic Ovary Syndrome (PCOS): PCOS can cause weight gain, fatigue, and difficulty concentrating. While it primarily affects women of reproductive age, its symptoms can overlap with those of a hormone imbalance.
• Cushing's Syndrome: This rare endocrine disorder is caused by excess cortisol production. Symptoms include weight gain, fatigue, and puffiness of the face (moon face), which align with some of the described symptoms.
• Adrenal Insufficiency: This condition, where the adrenal glands do not produce adequate amounts of hormones, can lead to fatigue, weight loss (though sometimes weight gain), and difficulty concentrating.

Do Not Miss Diagnoses

• Pituitary Tumor: Although rare, a tumor in the pituitary gland can affect hormone production, leading to a variety of symptoms including fatigue, weight changes, and visual disturbances due to the puffiness around the eyes.
• Diabetes Mellitus: Uncontrolled diabetes can lead to fatigue, weight changes, and difficulty concentrating. The puffiness around the eyes could be related to fluid retention or other associated conditions.
• Sleep Apnea: This condition can cause persistent fatigue and difficulty concentrating, and is associated with weight gain. While not directly a hormone imbalance, it can significantly impact quality of life and should not be overlooked.

Rare Diagnoses

• Addison's Disease: A rare disorder of the adrenal glands, Addison's disease can cause fatigue, weight loss, and changes in skin pigmentation, among other symptoms.
• Growth Hormone Deficiency: This condition can lead to fatigue, weight gain, and difficulty concentrating, though it is less common and typically presents with additional symptoms such as decreased muscle mass and bone density.
• Prolactinoma: A type of pituitary tumor that causes an excess of prolactin, leading to a variety of symptoms including weight gain, fatigue, and visual disturbances, though galactorrhea (spontaneous milk production) is a more distinctive symptom.