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  • Is Misdiagnosis Possible After Reading an Athlete's Lab Test Results?

    Is Misdiagnosis Possible After Reading an Athlete’s Lab Test Results?

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    Is Misdiagnosis Possible After Reading an Athlete’s Lab Test Results?

Physical exercise and exercise intensity can influence laboratory test results resulting in misdiagnosis and unnecessary examinations if the physician is unaware of the patient’s training history. Acute exercise, including aerobic exercise and endurance training, can blast your body with uric acid, causing misreads for blood sugar and other body mass index testing. Let’s explore the effect of physical exercise on laboratory test results, LDL cholesterol, glucose concentration, free fatty acids, and more with Ehline Law and our injury attorneys.

Effect of Physical Exercise on Laboratory Test Results

The following are findings from studies exploring the relationship between physical exercise, cardiovascular risk, and some plasma volume and blood volume indicators on lab tests.

Complete Blood Count

Acute physical exercise can have a significant impact on the red blood cell count due to hemoconcentration, which increases the following concentrations between 10% and 30%:

  • Hematocrit
  • Hemoglobin
  • Erythrocyte.

The percentage change depends on the intensity and duration of the exercise. Short physical activity, such as sprinting, elevates all three indicators, returning to the normal range within 30 minutes.


Depending on the intensity of the physical exercise, there is a significant change in leukocytosis. For example, in intense exercise training, leukocytosis can reach twice the normal levels, while it immediately jumps up by between 50% and 100% after an endurance exercise. Not many studies examine the white blood cell count and alkaline phosphatase in endurance athletes (female and male athletes.)

Fibrinolytic System

After a marathon run or strenuous exercise, marathon runners showed a significantly shorter euglobulin lysis time while having a significantly elevated degradation product B and D-dimer concentration, even with increased fluid intake and expected electrolyte balance. It also increases the tissue plasminogen activator almost 30 times before returning to normal after three hours.

Study shows that exercise training results in the following statistical significance:

  • Increased coagulability
  • Increased activated inhibitor potential laboratory tests.

Since coagulation remains longer than fibrinolysis, the recovery phase can cause thromboembolic events in some patients. Investigations reveal that physical exertion does not consistently affect the fibrinolytic system, but it does affect the fibrinolytic activity. Independent analysis of fibrinogen can be a great indicator of cardiovascular disease and other inflammatory markers.

Hemostatic System

The 1986 study published in the Journal of Applied Physiology that studies the effects of a marathon race on blood platelet activation and thrombin activity revealed the following:

  • No effect on the prothrombin time and reference intervals
  • The Activated partial thromboplastin time is much shorter during exercise and remains that way even after three hours of marathon running along with other biochemical parameters.
  • A marathon run can result in an increased fibrinogen concentration. However, regular endurance exercise can result in an average decrease of 40 mg/dL in fibrinogen concentration.
  • An increase in the prothrombin fragment
  • Short-term intense workouts can result in an increased thrombin-antithrombin complex.

Anemia Diagnostics

A study by Eichner ER in 1986, published in The Physician and Sportsmedicine journal, revealed that athletes could develop anemia. However, evaluating the red blood cell count is rather complex, and the physician must consider changes in complete blood cell count as well as physiological adaptation.

Other Blood Compounds

Several studies conducted in the past showed the impact of physical activity on other blood compounds and platelet counts, including sodium, potassium, magnesium, and red blood cells.

  • The levels of sodium depend on water metabolism. In the study published in Medicine & Science in Sports & Exercise in 1999, the findings revealed no effect on sodium levels following a short or moderate exercise. However, endurance training, especially among women, could lead to hyponatremia, but it is often asymptomatic. Severe complications of hyponatremia in marathon runners could lead to cerebral edema, brain herniation, and seizures due to increased intracranial pressure if left untreated.
  • A 1989 study published in the International Journal of Sports Medicine revealed a decrease in potassium in skeletal muscles upon exercise, which forces muscle cells to release potassium, accumulating quickly in the blood. These often return to normal levels rapidly, but if the blood takes in too much potassium from the muscle cells, it can lead to mild hypokalemia.
  • In a 2002 study published in the Deutsche Zeitschrift für Sportmedizin, the findings revealed after an endurance exercise, magnesium enters the erythrocytes, causing a decrease in plasma magnesium levels. There is a deficiency of magnesium among athletes as it leaves the body through excretion.
  • A 2016 study published in the Open Access Journal of Sports Medicine​ revealed that regular exercise could increase the levels of red blood cells in the body, and a low red blood cell count can indicate anemia, iron deficiency, or a combination of both.

Blood/Protein in Urine

Traces of blood or protein is often detected in urine after 24 to 48 hours of exercise due to repetitive muscle breakdown. Exercise or endurance training can also increase the muscle enzyme creatine kinase in the body, but these often return to normal levels after a week of recovery and rehydration.

Hydration and Blood Cells

Sweating from exercise or intaking too much fluids can affect hydration levels in the body, resulting in high or low levels of red and white blood cells and creatine concentrations, both being a serious concern.

Insulin and Blood Glucose Levels

When exercising, glucose levels in the blood can drop significantly to counteract the side effects of muscle contraction. During this time, the liver excretes more glucose to the muscles causing an increase in blood glucose levels and decreasing blood insulin. The blood test results may seem worrisome if they lead to medical conditions.

Does a Doctor Only Use Blood Test Results for Diagnosis?

The doctors use results from blood tests to help diagnose patients. However, because there can be changes in blood test results due to exercise, physicians also use other indicators, such as blood pressure, pulse, and symptoms, for accurate diagnosis.

Schedule a Free Consultation with Ehline Law

Doctors must stay updated on all the latest studies and consider all factors before diagnosing a patient, as misdiagnosis can further affect a patient’s health. If you suffered injuries or deteriorating health due to misdiagnosis, contact us at (833) LETS-SUE for a free consultation, as you may be eligible for compensation.


Michael Ehline

Michael Ehline is an inactive U.S. Marine and world famous legal historian. Michael helped draft the Cruise Ship Safety Act and has won some of the largest motorcycle accident settlements in U.S. History. Together with his legal team, Michael and the Ehline Law Firm collect damages on behalf of clients. We pride ourselves in being available to answer your most pressing and difficult questions 24/7. We are proud sponsors of the Paul Ehline Memorial Motorcycle Ride, and a a Service Disabled Veteran Operated Business. (SDVOB.) We are ready to fight.

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