A Closer Look At Advances In Functional Lab Testing
- Volume 19 - Issue 8 - August 2006
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The modern podiatric physician is faced with many challenges when it comes to appropriate patient selection for surgical procedures. Specifically, when it comes to the high-risk patient with diabetes, there are potential challenges that can lead to postoperative complications and potential lawsuits. Indeed, some of these high-risk patients may experience delayed wound healing with no obvious preoperative disease elucidated in the preoperative history, physical and conventional laboratory studies.
Faced with these challenges, the astute podiatric physician now has the ability to order functional laboratory testing that will help ascertain a patient’s ability to heal postoperatively and reduce the incidence of postoperative infections. Accordingly, let us take a closer look at some of the most reliable functional tests available to podiatric physicians that can aid them in assessing potential risks of patients who have compromised health.
Understanding The Potential Impact Of Hypercortisolemia
In our fast-paced society, many Americans are subjected to chronic stress, which influences the body’s ability to produce a normal circadian rhythm of cortisol from the adrenal glands.
Cortisol is a very powerful intrinsic hormone (see “Inside Insights On Cortisol Production” below) and can function as a catabolic hormone. For example, when blood sugar is low, cortisol stimulates the breakdown of protein and fat to produce glucose to counteract the low blood sugar. Cortisol is also important in moderating inflammation. Inflammation can result in greater damage to tissues than the original trauma that caused the inflammation. The adrenal glands increase cortisol production to control the inflammatory response. Cortisol also takes part in the regulation of blood volume and blood pressure by reducing the loss of sodium in the urine. Cortisol also helps to maintain emotional stability.
All of these cortisol effects assist the body in dealing with physical and emotional trauma and stress. Increased adrenal stress may also occur among patients who are undergoing operative procedures. There is the emotional stress of the contemplated surgical procedure. There is also the physical stress of the anesthetic and the surgical stress of tissue insult to both soft tissue and bone.
Chronically elevated cortisol, as the result of the aforementioned stressors, has many detrimental effects on the body. Hypercortisolemia causes increased protein breakdown and decreased protein synthesis. This effect can result in loss of muscle mass. A decrease in protein synthesis will also result in accelerated aging of the skin. Protein synthesis is essential for adequate soft tissue and postoperative bone healing.
Excess cortisol promotes osteoporosis by enhancing the breakdown of the protein matrix, which retains minerals in the bone and reduces the synthesis of the protein matrix for the formation of new bone. Accordingly, hypercortisolemia results in delayed bone healing for procedures involving osteotomies. Hypercortisolemia may also delay bone healing in fracture repair due to the aforementioned breakdown of protein matrix.
Hypercortisolemia will also reduce the uptake and utilization of intracellular glucose. This reduction has a significant effect on brain function since intracellular glucose is the optimum fuel for the cells of the brain and nervous systems.
Hypercortisolemia has a profound effect on the body’s immune system as it increases the body’s susceptibility to cancer cell growth. The increased protein breakdown secondary to hypercortisolemia and the decreased protein synthesis results in a decrease in lymph tissue with corresponding reductions in T cells and antibodies. There is also a dramatic reduction in production of secretory IgA in the presence of hypercortisolemia. This reduction increases the risks of bacterial and viral infections involving the respiratory, gastrointestinal, urinary and reproductive tracts. A low preoperative level of secretory IgA could increase the risk of a postoperative infection. Indeed, infectious agents disseminated from a site distant to the operative site could result in a postoperative infection.