Differential Diagnosis for Polyuria in a 75-year-old Female
Single most likely diagnosis
- Diabetes Mellitus: Given the symptom of polyuria, especially in a 75-year-old female, diabetes mellitus is a highly likely diagnosis. The body's inability to regulate blood sugar levels leads to increased glucose in the blood, which in turn increases glucose in the urine, causing polyuria.
Other Likely diagnoses
- Urinary Tract Infection (UTI): UTIs can cause irritation to the bladder, leading to a sensation of needing to urinate more frequently, which might be perceived as polyuria. In elderly females, UTIs are common due to factors like decreased mobility and hormonal changes.
- Overactive Bladder: This condition is characterized by a sudden, intense urge to urinate, sometimes accompanied by unintentional urination. It could be mistaken for polyuria, especially if the patient experiences small amounts of urine at night.
- Benign Prostatic Hyperplasia (BPH) is less likely in females but Bladder Outlet Obstruction due to other causes like pelvic organ prolapse could be considered.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Diabetic Ketoacidosis (DKA): Although more common in type 1 diabetes, DKA can occur in type 2 diabetes, especially in the context of infection, medication non-adherence, or other stresses. It's crucial to identify and treat promptly to avoid severe complications.
- Hypercalcemia: Can cause polyuria due to its effect on the kidneys' ability to concentrate urine. Hypercalcemia can be due to primary hyperparathyroidism, malignancy, or other causes, and missing it could lead to severe consequences.
- Pituitary or Suprasellar Tumors: Although rare, tumors affecting the pituitary gland can lead to central diabetes insipidus, characterized by polyuria. Missing this diagnosis could lead to delayed treatment and significant morbidity.
Rare diagnoses
- Nephrogenic Diabetes Insipidus: A rare condition where the kidneys are unable to concentrate urine despite normal or elevated antidiuretic hormone (ADH) levels. This could be due to genetic causes, certain medications, or kidney diseases.
- Psychogenic Polydipsia: A condition where excessive fluid intake leads to polyuria. This might be seen in patients with psychiatric disorders or as a factitious disorder.
- Central Diabetes Insipidus: As mentioned, this is a rare condition that could be due to various causes affecting the hypothalamus or pituitary gland, leading to a deficiency in ADH production.