Which of the following conditions results from a lack of PTH?

Tetany occurs as a result of hypoparathyroidism, which is characterized by low levels of parathyroid hormone (PTH). PTH plays a crucial role in regulating calcium levels in the blood, promoting the release of calcium from bones, absorption of calcium in the intestines, and conservation of calcium in the kidneys. When there is an insufficient amount of PTH, calcium levels in the blood can drop, leading to hypocalcemia.

The symptoms associated with hypocalcemia include muscle cramps, spasms, and tetany, which are involuntary muscle contractions that may cause severe discomfort and potentially life-threatening situations. The presence of these symptoms indicates that the body is not properly regulating its calcium levels due to the absence of PTH.

The other conditions mentioned do not directly relate to the lack of PTH. Inflammation is generally associated with immune responses or injury, jet lag pertains to circadian rhythm disturbances due to travel across time zones, and acromegaly is caused by an excess of growth hormone, typically due to a pituitary tumor. None of these conditions arise from the mechanisms involving parathyroid hormone and calcium metabolism.