Which effects are caused by low serum calcium levels in relation to parathyroid hormone?

Low serum calcium levels trigger a physiological response aimed at restoring calcium balance in the body. Parathyroid hormone (PTH) plays a crucial role in this process. When serum calcium levels drop, PTH is secreted to help increase calcium concentration in the bloodstream.

One key effect of PTH is the increased absorption of calcium from the intestines. It enhances the conversion of vitamin D into its active form, which in turn boosts intestinal absorption of calcium. Additionally, PTH works to minimize calcium loss in the urine by influencing the kidneys to reabsorb calcium more effectively. This dual action—enhancing intestinal absorption and reducing renal excretion—results in an overall increase in serum calcium levels.

While considerations regarding calcium absorption and urinary loss are relevant, the option highlighting increased absorption from the intestines and minimized loss in urine encapsulates the main hormonal responses aligned with low serum calcium levels and the activity of parathyroid hormone.