Benign nocturnal leg cramps: This is the most common cause of lower extremity cramping, often occurring at night and affecting the calf muscles. It is usually idiopathic but can be related to factors like dehydration, electrolyte imbalance, or certain medications.

Electrolyte imbalance (e.g., hypokalemia, hypocalcemia, hypomagnesemia): Imbalances in essential electrolytes can lead to muscle cramping, including in the lower extremities. This can be due to various reasons such as poor diet, excessive sweating, or certain medical conditions.
Dehydration: Inadequate fluid intake or excessive fluid loss can lead to dehydration, which is a common cause of muscle cramps.
Overuse or muscle strain: Physical activity that is strenuous or unfamiliar can lead to muscle cramping in the lower extremities.
Medication side effects: Certain medications, such as diuretics, can cause electrolyte imbalances leading to cramping.

Deep vein thrombosis (DVT): While less common, DVT can present with cramping in the lower extremity, among other symptoms like swelling and warmth. Missing this diagnosis can be fatal due to the risk of pulmonary embolism.
Peripheral artery disease (PAD): Cramping in the lower extremities during exercise (intermittent claudication) can be a symptom of PAD, which requires prompt medical attention to prevent serious complications.
Neurological disorders (e.g., peripheral neuropathy): Certain neurological conditions can cause cramping, numbness, or tingling in the lower extremities. Early diagnosis is crucial for effective management.

Hypothyroidism: In some cases, hypothyroidism can lead to muscle cramps, including in the lower extremities, though this is less common.
Addison's disease: This rare endocrine disorder can cause a variety of symptoms, including muscle cramps, due to adrenal insufficiency.
Sarcoidosis: A rare condition that can affect multiple parts of the body, including the muscles, leading to cramping among other symptoms.