Differential Diagnosis for a 90-year-old Female with Frequent Urination at Night

Single Most Likely Diagnosis

• Nocturia due to Benign Prostatic Hyperplasia (BPH) or Overactive Bladder: This condition is common in the elderly and can be exacerbated by factors such as decreased bladder capacity, increased urine production at night, or sleep disorders. However, given the patient's gender, overactive bladder is more likely.

Other Likely Diagnoses

• Urinary Tract Infection (UTI): Elderly individuals are more prone to UTIs, which can cause frequent urination, especially at night. Symptoms might be atypical, making diagnosis challenging.
• Diabetes Mellitus: Uncontrolled diabetes can lead to polyuria (frequent urination), which may be more noticeable at night.
• Congestive Heart Failure (CHF): CHF can cause nocturia due to increased fluid redistribution and increased urine production when lying down.
• Sleep Disorders: Conditions like sleep apnea can lead to increased urine production at night due to increased pressure on the heart and subsequent release of atrial natriuretic peptide.

Do Not Miss Diagnoses

• Renal Failure: Acute or chronic kidney disease can lead to polyuria. Missing this diagnosis could lead to severe complications if not addressed promptly.
• Hypercalcemia: Elevated calcium levels can cause polyuria. This condition can be life-threatening if not treated.
• Pheochromocytoma: Although rare, this tumor can cause nocturia among other symptoms like hypertension and palpitations. Missing this diagnosis could be fatal.

Rare Diagnoses

• Diabetes Insipidus: A condition characterized by the inability to regulate fluids in the body due to problems with the antidiuretic hormone (ADH). It's rare but could present with nocturia.
• Graves' Disease: Hyperthyroidism can cause increased urine production. While not the first consideration, it's a possibility in the differential diagnosis of nocturia.

Each of these diagnoses requires careful consideration of the patient's medical history, physical examination, and potentially, further diagnostic testing to determine the underlying cause of her nocturia. Management will depend on the specific diagnosis but may include lifestyle modifications, medication, or other interventions tailored to the patient's condition.