Diabetes Mellitus: This condition is characterized by high blood sugar levels, which can lead to increased urine production (polyuria) as the body tries to eliminate excess glucose. The symptoms of frequent urination, especially when combined with increased thirst and hunger, make diabetes mellitus a top consideration.

Diabetes Insipidus: A condition where the body is unable to regulate fluids due to a problem with the antidiuretic hormone (ADH), leading to excessive thirst and urination.
Urinary Tract Infection (UTI): Infections in the urinary system can cause irritation to the bladder and urethra, leading to a frequent need to urinate.
Benign Prostatic Hyperplasia (BPH): Enlargement of the prostate gland can press against the urethra, affecting urine flow and leading to frequent urination.
Overactive Bladder: A condition characterized by a sudden, intense urge to urinate, sometimes accompanied by unintentional urination.

Kidney Disease: Chronic kidney disease or acute kidney injury can lead to changes in urination frequency and should not be missed due to their potential for severe consequences.
Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodes of hypertension, sweating, headache, and palpitations, and may also lead to increased urination.
Hypercalcemia: Elevated calcium levels in the blood can cause increased urination among other symptoms, and is crucial to diagnose due to its implications for various bodily systems.

Nephrogenic Diabetes Insipidus: A rare condition where the kidneys are unable to respond to ADH, leading to an inability to concentrate urine and resulting in polyuria.
Primary Polydipsia: A condition characterized by excessive thirst and fluid intake, leading to polyuria, which can be psychological in origin or due to certain medical conditions.
Graves' Disease: Although primarily known for causing hyperthyroidism, Graves' disease can also lead to increased urination among its myriad symptoms.