If calcium levels are low and PTH levels are normal or low, then PTH is not responding properly and the person tested probably has hypoparathyroidism. Hypoparathyroidism is a failure of the parathyroid glands to produce sufficient PTH.
Heat exhaustion definition and facts. 1  Heat exhaustion is one part of the spectrum of heat-related illnesses that begin with heat cramps, progresses to heat exhaustion, and finally to heat stroke.  The body cools itself by sweating and allowing that sweat to evaporate.
Both of these are due to excessive sun exposure. But, the main difference between heat stroke and heat exhaustion is, heat exhaustion occurs when a person is severely exhausted and is not hydrated properly. Lack of fluid in body or fluid, electrolyte imbalance leads to heat exhaustion.