Urinary Tract Infection (UTI): This is often the most common cause of frequent urination, especially in women. Symptoms can include dysuria, urgency, and suprapubic discomfort.

Diabetes Mellitus: Both type 1 and type 2 diabetes can cause frequent urination due to high blood sugar levels leading to increased glucose in the urine, which pulls water with it, increasing urine output.
Benign Prostatic Hyperplasia (BPH): Enlargement of the prostate gland can compress the urethra, leading to urinary frequency, urgency, and nocturia in men.
Overactive Bladder: A condition characterized by a sudden, intense urge to urinate, sometimes accompanied by unintentional urination. It can be caused by various factors, including neurological disorders, certain medications, and bladder issues.

Diabetic Ketoacidosis (DKA): A serious complication of diabetes that can lead to severe illness or death if not promptly treated. Frequent urination can be an early sign, along with hyperglycemia, metabolic acidosis, and ketosis.
Kidney Stones: While not always immediately life-threatening, kidney stones can cause severe pain and, if obstructing the urinary tract, can lead to serious complications like sepsis or kidney damage.
Pregnancy: Frequent urination can be an early sign of pregnancy due to hormonal changes and pressure on the bladder. Missing this diagnosis could lead to delayed prenatal care.

Bladder Cancer: Though less common, bladder cancer can cause changes in urination patterns, including frequency. It's more common in older adults and those with a history of smoking.
Neurogenic Bladder: A condition resulting from a lack of bladder control due to a brain, spinal cord, or nerve problem. It can lead to a variety of urinary symptoms, including frequency.
Interstitial Cystitis: A chronic condition causing bladder pressure, bladder pain, and sometimes pelvic pain. The symptoms can worsen as the bladder fills and may improve with urination.