Final answer:
ADH secretion typically rises with serum osmolarity (sOSM), helping to regulate water balance in the body by increasing water retention and decreasing urine volume, which in turn lowers blood osmolarity back to normal levels.
Step-by-step explanation:
Typically, antidiuretic hormone (ADH) secretion should increase with serum osmolarity (sOSM). When serum osmolarity rises, indicating a higher concentration of solutes in the blood, the hypothalamus detects this change and stimulates the secretion of ADH. The function of ADH is to conserve water in the body by reducing urine volume and returning water back to the blood, thus decreasing blood osmolarity towards normal levels. As a result, the total body water (TBW) increases, although ADH does not directly affect body sodium concentration or osmolarity (Na/OSM).
ADH also acts on the kidneys to promote water retention, which contributes to decreased urine sodium excretion and increased urine osmolarity (uOSM). High levels of ADH can lead to water retention and vasoconstriction, affecting blood pressure regulation. When the initial osmolar imbalance is corrected, a negative feedback mechanism decreases ADH levels, allowing osmolarity to stabilize at a normal range.