Why do patients with undiagnosed diabetes often present with increased frequency of urination?

Correct Answer: C

Rationale: In diabetes mellitus, high blood glucose exceeds the renal threshold, leading to osmotic diuresis where glucose in the urine prevents water reabsorption, causing polyuria.

Correct Answer: D

Rationale: Serum Na, or serum sodium, is regulated by both blood pressure (BP) and kidney perfusion, which play a crucial role in maintaining the balance of sodium in the body. Additionally, serum sodium levels are regulated by hormones such as aldosterone and ADH, which help control reabsorption and excretion. Serum Na also reflects blood osmolality, a measure of solute concentration in the blood. The option 'Not affected by K pumps' is incorrect as potassium-sodium pumps influence sodium levels, but the first three statements are true.

Correct Answer: D

Rationale: Approximately $99% of the body's calcium is stored in the bones. Calcium is an essential mineral for bone health and plays a crucial role in maintaining their strength and structure. It is constantly being deposited and withdrawn from the bones in a process called bone remodeling, balancing blood calcium levels.

Correct Answer: C

Rationale: Chvostek sign is a clinical sign that involves the facial nerve (cranial nerve VII). It is demonstrated by tapping on the facial nerve, usually at the angle of the jaw. A positive Chvostek sign is indicated by the twitching of the facial muscles, particularly the muscles around the mouth and eye, often seen in hypocalcemia.