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Cold feet with fever in a child
Last reviewed: 07.06.2024
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The essence of an increase in body temperature (fever) is the strengthening of the adaptive response of the body due to the activation of immune system cells in response to infection. However, with an elevated temperature, the child's feet may be cold. And this is observed in most children.
Why does a child's feet feel cold when they have a fever?
If we do not go into details, we can say that the reasons that lead to a decrease in the temperature of the lower extremities in fever lie directly in the very high temperature in a child.
The increase in body temperature that manifests itself as a symptom is due to the action of substances (signaling molecules) that cause fever - pyrogens (from Greek pyr - fire and genos - genus). Bacterial or viral toxins, which are exogenous pyrogens, act first; their action causes an immune response, i.e. Activation of chemokines, mononuclear phagocytes, B-cells and T-lymphocytes, as well as the production of cytokines - interleukin-1 (IL-1) and interleukin-6 (IL-6). These cytokines produced by activated immune cells (including cells lining the inner surface of blood vessels endothelium) are the main endogenous pyrogens.
And already induced interleukins, released into the bloodstream in response to exogenous pyrogens and acting on the thermoregulatory center of the hypothalamus, cause an increase in body temperature.
Pathogenesis
Pathogenesis, more precisely, the biochemical and physiological mechanism of lower extremity temperature reduction at elevated body temperature is vasoconstriction (from Latin vaso - vessel and constrictio - constriction") - narrowing of blood vessels in the legs by contraction of muscle fibers of their walls. As a result, the lumen of blood vessels decreases with restriction of blood circulation. And this process is normal (i.e. Does not require treatment).
Fever is generated by the body's immune system, and when the temperature receptors of the hypothalamic sensory neurons - which are centered in its preoptic region and control absolute and relative temperature changes - respond to IL-1 and IL-6 signals, a so-called "set point" or increase in the thermostatic set point is set. And this causes the body to produce more heat under the control of the balance between its production and loss by the hypothalamic thermoregulation center.
As increased body temperature leads to increased metabolic costs and increased oxygen demand of the most important organs, at the same time the immune system releases neurotransmitters that cause constriction of blood vessels in the lower extremities, in particular angiotensin II. Thus, by temporarily restricting blood flow in the lower extremities, more nutrients and oxygen are delivered to the organs that need them most.
In this case, when the body reaches the thermostatic point set by the hypothalamus, there is a dilation of blood vessels, and the feet of children with fever become warm.
By the way, different parts of the body have different temperatures, and toes have the lowest temperature. In addition, the extremities have the fewest skin thermoreceptors.