Which condition is usually caused by ineffective PTH?

Hypoparathyroidism is typically associated with ineffective parathyroid hormone (PTH) activity, leading to hypocalcemia. PTH is responsible for regulating calcium levels in the blood; it acts to increase calcium levels by stimulating the release of calcium from bones, increasing reabsorption of calcium in the kidneys, and promoting the activation of vitamin D to enhance intestinal absorption of calcium.

When PTH is ineffective or insufficient, as seen in conditions like hypoparathyroidism, there is decreased mobilization of calcium reserves from the bones and reduced renal reabsorption of calcium, resulting in lower serum calcium levels (hypocalcemia). This can manifest clinically with symptoms such as muscle cramps, spasms, and tingling sensations.

In contrast, high calcium levels in the blood (hypercalcemia) are associated with conditions such as primary hyperparathyroidism, where there is excess PTH activity. Respiratory acidosis and metabolic alkalosis relate to issues with carbon dioxide retention or loss of acid, respectively, and are not directly associated with PTH activity or calcium regulation.