Dry Skin (Xerosis): This is a common condition, especially in older adults, due to decreased moisture in the skin. Itching at night can be exacerbated by dry environments, such as heated homes during winter, and is often worse on the lower extremities.

Eczema (Atopic Dermatitis): A chronic condition characterized by itchy, inflamed skin. It can appear anywhere on the body and is often worse at night.
Contact Dermatitis: An allergic or irritant reaction to substances coming into contact with the skin, which can cause itching, especially if exposure occurs before bedtime.
Flea or Insect Bites: If the patient has pets or has been outdoors, flea or insect bites could cause localized itching, especially if the bites are on the lower extremities.
Restless Legs Syndrome: While primarily known for causing an urge to move the legs, it can also cause itching sensations, especially at night.

Lymphoma or Leukemia: Certain types of blood cancers can cause itching all over the body, including the lower extremities, due to the release of various chemical mediators.
Thyroid Disorders: Both hyperthyroidism and hypothyroidism can cause itching, though the mechanism is not fully understood.
Kidney or Liver Disease: Itching can be a symptom of advanced kidney or liver disease due to the buildup of toxins in the blood.
Multiple Myeloma: A type of blood cancer that can cause itching due to the release of certain proteins.

Polycythemia Vera: A rare blood disorder that can cause itching, particularly after warm baths or showers, due to the release of histamine from basophils.
Notalgia Paresthetica: A condition characterized by itching on the upper back but can sometimes be reported on other areas, including the lower extremities, due to nerve irritation.
Brachioradial Pruritus: Though typically affects the arms, it's a condition causing intense itching due to nerve damage, which could potentially affect the lower extremities in rare cases.