The most important test for heatstroke is the CBC. In this, a blood sample is taken from the patient (3 ml for adult and 1 ml for child). Clotted specimens are rejected. This blood sample is then subjected to various blood related tests, such as white blood cell count, red blood cell count, hemoglobin and platelet count. In heatstroke, hemoglobin and water may be found in low volumes. Discrepancies in other blood tests may appear.

Heatstroke usually occurs due to overworked muscles. Due to undue exertion, cells in the muscles tend to get affected as well, along with their inability to cope with the rising temperature. So, tests are done to check metabolism of the body in order to find out how much stress and heat the body can absorb, and whether overexertion is the real reason for heatstroke. This test is also important as it helps in determining the health of muscle tissues.

Prothrombin time is a method of measuring clotting time by plasma recalcified in the presence of excess tissue thromeboplastin. It is used to check the change in blood properties. As diseases like liver diseases, vitamin K deficiency and dysfibrinogenemia may also lead to heatstroke, ProTime test helps in determining whether the patient is suffering from one of these diseases or he/she is merely affected by heatstroke.

In Partial Thromboplastin Time test, the measurement of the duration of time taken by clotting to occur is observed. This is also used to check the prevalence of a disease, along with keeping a tab on the extent to which heatstroke has occurred. For a normal, healthy person, the test should generate the result in the range of 25 to 41 seconds.

The blood carries oxygen and carbon dioxide, along with food, salts and water. These gases help in determining the health of the overall body. It is not always that heatstroke occurs due to exertion or external factors. If the tissues are not kept healthy enough to function properly, more heat may be generated than normal, leading to rise in body temperature that culminates in heatstroke. The best way to check the tissue health is to check for the gas content in blood. Two lab tests, artery puncture and artery line, are performed that help in determining the amount of gas present in the fluid. If the amount of oxygen is low or/and the amount of carbon dioxide is high, efficiency of circulatory system comes under the scanner.

Creatine Kinase is a transferase, an enzyme that is responsible for helping a functional group to attach itself to the main compound. It catalyzes the attachment of phosphorus ion to ATP, thus giving rise to phosphocreatine from ATP + creatine. The ATP energy is stored as phosphocreatine in muscles and brain, and helps in keeping ATP constant for metabolism in the body. If creatine phosphokinase increases beyond permissible limits, the muscle tissues are severely affected that can lead to situations like heatstroke and muscle disorder. This test is rarely used, and is preferred only for distinguishing a muscle related disorder.

Urinalysis is one of the most common tests done for a disease. In this, the patient’s urine is collected in a container (minimum 3 ml). It is then subjected to reagent test (reaction of urine with reagents to check urine’s chemical composition) and urine microscopic exam (to check for pathogens and other microscopic bodies in urine). Apart from that, color, odor, specific gravity and pH level of urine is also taken into account. Comparing the data acquired with the data of an ideal healthy person, the final cause of fatigue is determined.