Hector Osorio 30 Jun 2020

The concept of laboratory testing has (in one form or another) been present in human history since the ancient times, however, the modern methods that we use and know today started to appear around the 19th century [1]. The contemporary lab results sheet is therefore the culmination of a long development process of medical techniques and knowledge. Although only your doctor can help you make the right decisions about your healthcare, we have written this article to provide some guidelines to help you understand what your test results might mean.

1. Iron

Reference range: 60-175 µg/dl

Role in your body: Iron is an essential element (not synthetized by the human body) of critical importance in DNA synthesis, production of red blood cells, oxygen transportation through the body and many other basic processes required to sustain life [3].

Excess: Is the main feature of hemochromatosis and it can also cause fatigue, palpitations, joint pains, impotence, abdominal pains, cardiovascular problems, changes in your skin color, liver problems, depression, elevated blood sugar and pituitary gland problems [4].

Deficiency: Is usually asymptomatic but it can manifest as weakness, difficulty concentrating, higher risk of infection and greater predisposition to heart failure [5].

2. Vitamin B

Reference range: B6: 5-50 µg/L – B12: 200-900 pg/ml

Role in your body: B6: This vitamin is a powerful antioxidant and facilitates a large number of enzymatic reactions which are important for the proper functioning of the metabolism (sugar and fat processing) [6]. B12:  Has important roles in the maintenance of DNA synthesis, nerve tissue and blood cells [7].

Excess:  B6: Can cause loss of muscle control, painful skin lesions, heartburn, nausea, numbness and photosensitivity [8]. B12: any excess is usually eliminated through urine, but in some cases, high levels can lead to nausea, vomiting, dizziness and headaches [9].

Deficiency: B6: This one is rather unusual, but in such cases, people experience depression, confusion, weak immunity, scaling and cracks on the mouth, swollen tongue and problems absorbing other nutrients [10]. B12: Can cause blood disorders, neurological disorders, irritability, memory impairments, dementia and increased risk cardiovascular problems [11]. 

3. Vitamin C

Reference range: 0.6-2 mg/dL

Role in your body: It mainly functions as an antioxidant helping you fight free radicals which can cause tissue damage and promote aging, also, is involved in several enzymatic processes related to metabolism [12].

Excess: In extreme cases, excessive vitamin c ingestion can lead to some forms of liver deficiency [13], diarrhea, nausea, vomiting, heartburn, abdominal cramps, headache and insomnia [14].

Deficiency: Bruising, bleeding gums, weakness, fatigue and rash can manifest as the patient develops scurvy [15].

4. Vitamin D3

Reference range: 20-50 ng/ml

Role in your body: This vitamin is necessary for calcium absorption into your bones, which keeps them strong and healthy [16].

Excess: With extremely high levels of this vitamin the body could suffer from hypercalcemia which could lead to vomiting, weakness, frequent urination and potential kidney problems [17].

Deficiency: The main consequences include nutritional rickets and soft bones [18].

5. Thyroid

Reference range : T3: 80-180 ng/dl,  T4: 4.6-12 µg/dl, TSH: 0.4-4 mU/L

Role in your body: These hormones in general play important parts in the regulation of your metabolism and have an effect over your cardiovascular, gastrointestinal and nervous systems. THS: It controls the release of other thyroid hormones [19].

Excess: High levels of T3 and T4 are a clear sign of hyperthyroidism which in severe cases leads to delirium, severe tachycardia, fever, vomiting, diarrhea, and dehydration [20]. In the case of TSH, high levels usually indicate hypothyroidism (joint pain, cold intolerance, constipation, depression, difficulty concentrating, menorrhagia, myalgias, weakness, weight gain, dry skin, fatigue, hair thinning/hair loss, memory impairment) [21].

Deficiency: low T4 and T3 usually signal a degree of hypothyroidism, meanwhile, low TSH indicates hyperthyroidism.

6. Hba1c

Reference range: 42 mmol/mol (6%)

Role in your body: The Hba1c is a molecule produced when blood glucose reacts with the hemoglobin in red blood cells. Measuring the amount of this chemical is considered as a good method to keep track of the development of type 2 diabetes over the last 2 to 3 months [22].

Excess: High levels have been associated with the development of diabetes, increased risk for coronary disease and stroke [22].

Deficiency: Abnormally low levels are very rare and not usually related to any clinical problem, however, it can be an indicator of low hemoglobin levels (anemia) [23].

7. Glucose

Reference range: 70-100 mg/dl (fasting)

Role in your body: Glucose is an important energy source for the human body. Its levels rise after a meal and then gradually decrease during the following hours [24].

Excess: (Hyperglycemia) nausea, vomiting, shortness of breath, dry mouth, weakness, confusion, coma, abdominal pain [25].

Deficiency: (Hypoglycemia) Irregular heartbeat, fatigue, Pale skin, Shakiness, Anxiety, Sweating, Hunger, Irritability, Tingling or numbness of the lips, tongue or cheek, Confusion, abnormal behavior or both, such as the inability to complete routine tasks, Visual disturbances, such as blurred vision, Seizures, Loss of consciousness [26].

8. Cholesterol

Reference range: LDL: <100 mg/dL, HDL: >45 mg/dL

Role in your body: LDL: Known as bad cholesterol, this molecule can accumulate in the walls of arteries. HDL: Is known as good cholesterol because it can be easily absorbed and processed by the liver [27].

Excess: LDL: Increases the chances of a cardiovascular event like a heart attack or stroke [28]. HDL: Although counterintuitive, very high levels can have negative chronic effects that can increase the chances of cardiovascular disease and death [29].

Deficiency: LDL: Exceptionally low levels (<40 mg/dL) have been associated with cancer, stroke, depression and anxiety [30]. HDL: Worsening of cardiac and diabetic conditions [31].

9. Cortisol

Reference range: 10-20 µg/dL (morning), <5 µg/dL (afternoon)

Role in your body: Is an important steroid involved in the body’s response to stress and the fight/flight response. Is a key element on the release and control of adrenalin [32].

Excess: Very high levels can lead to developing Cushing syndrome and manifest as erectile dysfunction, infertility, low libido, fatigue, muscle weakness, depression, anxiety, loss of emotional control, headaches, impaired growth, weakening of the bones [33].

Deficiency: extreme fatigue, weight loss and decreased appetite, darkening of your skin (hyperpigmentation), low blood pressure, even fainting, salt craving, low blood sugar (hypoglycemia), nausea, diarrhea or vomiting (gastrointestinal symptoms) and abdominal pain [34].

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About the Author:
Hector Osorio is a cell biologist, research assistant and science/health content writer. He loves complex topics related to life sciences like cancer, viral infections and aging. He graduated from Central University of Venezuela Faculty of Sciences and worked as a research assistant for the Center of Experimental Medicine of the Venezuelan Center for Scientific Research (IVIC) for 5 years.


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