Diagnostic laboratory testing is a powerful tool that is often neglected in the management of chronic wounds. Laboratory evaluations can help make a diagnosis or give further information as to why a wound is not healing as expected. Lab findings can be diagnostic, prognostic or used to follow the evolution of a chronic process. Below are some common labs and their rationale for use in wound care.

Blood glucose

For years the fasting and post-prandial evaluation of blood glucose has been the cornerstone for the diagnosis and management of diabetes mellitus. A diagnosis of diabetes is confirmed with  2 fasting measurements >126 mg/dL or a random blood glucose >200 with the appropriate symptoms. Serial blood glucose after an oral load of glucose (oral glucose tolerance test) is also a classic tool for diagnosing diabetes. Once a diagnosis is confirmed serial measurements of blood glucose levels can be used to assess compliance with and response to therapy.

• Typically wound healing begins to become inhibited with blood glucose levels over 130 mg/dL
• Mechanism for wound healing delay is associated with microvascular damage decreasing oxygenation of tissue and by inhibition of white blood cell function

Hemoglobin A1c

Hemoglobin A1c (HbA1c) was initially used as a stable way to measure diabetes control over a 3 month period of time. As recently as 2009 it was also adopted by the American Diabetes Association as a tool to diagnose diabetes.

• HbA1c >6.5% is diagnostic of diabetes mellitus
• Controlled diabetes is associated with a HbA1c between 6.5-7%

Albumin

Albumin is an essential protein in wound healing and quantitative measurement of albumin is part of the basic nutritional screening of a patient with a chronic wound.

• Albumin is directly linked to adequate intake of calories and protein
• Low albumin <3.2 g/dL can lead to delayed wound healing
• The half-life of albumin is about 18 days giving you a long-term understanding of the patient’s nutritional status but it’s a poor marker for acute follow-up of nutritional status

Prealbumin

Prealbumin is the best marker for acute changes in nutritional status due to its typically short half-life of 2-3 days. It’s an important carrier protein for vitamin A and thyroxine.

• It’s generally accepted that a prealbumin >16g/dL is required for wound healing to occur

Complete Blood Count (CBC)

The CBC is composed of the WBC count, hemoglobin, hematocrit, platelet count and red-cell indices. This simple test can provide a deep level of insight into the ongoing biologic processes in a wounded patient

WBC count

• Elevated during acute infection and in hematologic malignancies
• Suppressed in immunocompromised states

Hemoglobin

• This is directly tied to oxygen transport in the body, the lower the hemoglobin the less oxygen is getting to the peripheral tissue.
• Low hemoglobin can also be a guide as to the possibility of underlying nutritional deficiencies such as iron, folic acid and vitamin B
• Hematologic malignancies and solid organ tumors can also be associated with low hemoglobin and often this can be the first diagnostic clue
• Errors in hematopoesis can be detected via a high or low hemoglobin, especially when paired with the red-cell indices

Platelets

• The initiators of the healing cascade, their proper function is critical in the orderly process of wound healing.
  • Suppressed levels can inhibit wound healing as their adhesion, degranulation and release of cytokines orchestrates the process of hemostasis and the wound healing cascade

More to come in part 2.