Which hormone causes water retention by increasing sodium reabsorption?

A. Generalized skin redness is incorrect because this is not a hallmark of vaso-occlusive crises. Skin redness may occur with infection or inflammation, but it does not specifically indicate sickle-cell complications.

B. Bleeding gums is incorrect because bleeding tendencies are not typical of sickle-cell anemia. Bleeding gums are more commonly associated with platelet disorders or vitamin C deficiency, not vaso-occlusion.

C. Joint pain is correct because a vaso-occlusive crisis occurs when sickle-shaped red blood cells obstruct small blood vessels, leading to reduced blood flow, ischemia, and tissue hypoxia. This results in severe pain, often in the joints, bones, chest, or abdomen, which is the hallmark symptom of a crisis. Other accompanying signs may include fever, swelling, and tenderness in affected areas. These pain episodes can be sudden, severe, and recurrent.

D. Bradycardia is incorrect because vaso-occlusive crises do not typically cause bradycardia. In fact, patients may develop tachycardia as a compensatory response to anemia or pain.

A. Elevation of the legs increases pain in those with varicose veins is incorrect because elevating the legs actually relieves discomfort. Elevation reduces venous pressure and improves blood return to the heart, which decreases pain, swelling, and the feeling of heaviness in the legs.

B. The main cause of varicose veins is atherosclerosis is incorrect because varicose veins are primarily caused by venous valve incompetence, leading to venous dilation and blood pooling, not by arterial plaque buildup. Atherosclerosis affects arteries, not veins.

C. Individuals with varicose veins are not likely to develop peripheral edema is incorrect because venous insufficiency can cause fluid to accumulate in the tissues, leading to peripheral edema, particularly in the lower extremities after prolonged standing or at the end of the day.

D. Standing for long periods of time increases the risk of developing varicose veins is correct because prolonged standing or sitting without movement increases venous pressure in the legs, which stresses vein walls and valves. Over time, this can lead to valve dysfunction, vein dilation, and varicose vein formation. Other risk factors include obesity, pregnancy, aging, and family history.