3 min read
From CBC and HbA1c to LFTs, RFTs, TSH, and lipid profiles, understanding these common blood tests can help you have more informed conversations with your doctor.
By Dr. Maria K. Jimmy
You’ve just had your blood drawn. Now, you’re staring at a lot of abbreviations on a lab report.
What does it all mean?
Blood tests are among the most commonly ordered investigations in medicine, whether you are attending a routine health check-up or visiting your doctor with symptoms like fatigue, fever, or unexplained weight changes.
Here’s the secret doctors know: your blood is a storyteller. It can reveal clues about infections, nutritional deficiencies, blood disorders, and even how well your organs are functioning.
But, blood tests do not provide a diagnosis on their own. Instead, they help doctors piece together a larger clinical picture by combining laboratory results with your symptoms, medical history, physical examination, and, when needed, imaging studies.
Complete Blood Count (CBC): More Than Just Haemoglobin
We have all been asked to get a CBC done.
While many people associate it only with anaemia, it is actually a a snapshot of the cells circulating in your blood.
A CBC evaluates red blood cells, white blood cells, haemoglobin, haematocrit, and platelets.
Together, these values can help identify infections, different types of anaemia, blood loss, and, in some cases, blood disorders such as leukemia.
Blood Sugar Tests: Looking Beyond a Single Reading
Type 2 Diabetes Mellitus may remain undiagnosed for years because it gradually creeps up without symptoms.
Fasting blood glucose reflects your blood sugar at a specific moment, whereas HbA1c estimates your average blood glucose over the previous two to three months. Together, these tests help diagnose diabetes, monitor treatment, and identify people at risk before complications develop.
Liver and Kidney Function Tests
Your liver and kidneys perform hundreds of essential functions every day, and routine blood tests help assess how well they are working.
Through Liver Function Tests (LFTs) we check enzymes like ALT and AST—proteins that leak into your blood when liver cells are stressed or damaged.
We also measure bilirubin—a pigment that can cause jaundice at elevated levels. Elevated levels can hint at fatty liver disease, hepatitis, or even medication side effects.
Kidney Function Tests (RFTs) measure markers such as creatinine and eGFR (Estimated Glomerular Filtration Rate).
A declining eGFR suggests reduced kidney filtration and may indicate chronic kidney disease, often before symptoms develop.
Thyroid and Cholesterol Tests
A Thyroid-Stimulating Hormone (TSH) test is usually the first step in evaluating thyroid function.
A simple TSH test tells us if the “thermostat” is set too high (hyperthyroidism, leading to weight loss and anxiety) or too low (hypothyroidism, leading to fatigue and weight gain). It influences everything from your mood to your menstrual cycle.
A lipid profile measures LDL (the “bad” that clogs arteries), HDL (the “good” that cleans up), and Triglycerides (fat storage).
Rather than focusing on a single number, doctors assess the overall pattern alongside other cardiovascular risk factors such as age, smoking, diabetes, blood pressure, and family history.
Vitamin and Iron Tests
Fatigue can sometimes be caused by nutritional deficiencies.
- Iron Studies & Ferritin: Iron deficiency is a common cause of anemia-related fatigue.
- Vitamin B12 & Folate: Crucial for nerve function and red blood cell production. A deficiency here can cause that “pins and needles” feeling or brain fog.
- Vitamin D: The “sunshine vitamin” is essential for bone health and immune function.
What Blood Tests Cannot Tell You
The most important thing to remember is that blood tests are only one part of medical diagnosis.
Laboratory values vary with age, sex, medications, pregnancy, and even temporary illnesses. This is why doctors interpret results within the context of your overall health.
The Bottom Line
Understanding what common investigations measure can make your reports less intimidating, but interpreting them correctly requires clinical context.
And that is what your doctor will do for you.
References
- Jameson JL, Fauci AS, Kasper DL, Hauser SL, Longo DL, Loscalzo J, editors. Harrison’s Principles of Internal Medicine. 21st ed. McGraw Hill; 2022.
- Rifai N, Horvath AR, Wittwer CT, editors. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier; 2023.
- McPherson RA, Pincus MR, editors. Henry’s Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Elsevier; 2021.
- American Diabetes Association. Standards of Care in Diabetes—2025.
- Kidney Disease: Improving Global Outcomes (KDIGO). 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease.
- American Thyroid Association. Clinical Practice Guidelines for the Diagnosis and Management of Thyroid Disease.
- American Heart Association. Understanding Cholesterol and Lipid Testing.
Important Note
This article is for educational purposes only and should not be used to self-diagnose or interpret blood test results. Always discuss your laboratory reports with a qualified healthcare professional, who can interpret them in the context of your symptoms, medical history, and examination. The accompanying image is AI-generated.
You may wish to read these next:
Dr. Maria K. Jimmy 