Final answer:
Diuretic therapy typically increases the excretion of Ca2+ in the urine. Loop diuretics specifically lead to a greater loss of Ca2+ due to their effect on the ascending limb of the loop of Henle. However, thiazide diuretics can actually decrease urine Ca2+ levels by increasing reabsorption in the distal convoluted tubule.
Step-by-step explanation:
Diuretic therapy typically influences urine Ca2+ levels by increasing their excretion. When diuretics like loop diuretics or thiazides are used, they inhibit the reabsorption of Na+ and Cl- ions in different parts of the nephron, leading to increased urine output. Due to regulatory effects, such as actions of the parathyroid hormone (PTH), low levels of Ca2+ in the blood can result in an increased reabsorption of Ca2+ from the urine; however, when diuretics are in play, this balance can be disrupted, causing more Ca2+ to remain in the urine and be excreted.
In the presence of loop diuretics, there is an increased loss of Ca2+ in urine since they can reduce the reabsorption of calcium in the loop of Henle. On the other hand, thiazide diuretics can lead to an increased reabsorption of calcium in the distal convoluted tubule, making these a unique case where diuretic therapy can decrease urine Ca2+ levels.