Quick answer
What Is Laboratory Tests?
Laboratory tests examine samples of blood, and sometimes urine, to assess the health of your heart and other organs. For heart patients, common tests include a lipid profile, blood sugar, kidney function, electrolytes, a complete blood count, troponin, and NT-proBNP. Your doctor reads the results together with your symptoms and other tests.
Sources01 / Understanding the procedure
About Laboratory Tests
Why Laboratory Tests Matter for Your Heart
Many things that affect the heart cannot be seen from the outside. Cholesterol, blood sugar, and kidney function can change without symptoms, yet they help determine the risk of heart and blood vessel disease. In certain situations, substances released by the heart muscle into the blood also help your doctor recognize a heart attack or heart failure.
Tests Cardiologists Often Request
- Lipid profile: total cholesterol, LDL, HDL, and triglycerides to assess the risk of narrowed blood vessels.
- Blood sugar and HbA1c: to detect diabetes or prediabetes, an important risk factor for heart disease.
- Kidney function and electrolytes: creatinine, urea, sodium, and potassium, which are also important before certain medicines or contrast agents are given.
- Complete blood count: hemoglobin, white blood cells, and platelets, for example to detect anemia, which can increase the heart's workload.
- Troponin: a marker of heart muscle damage used to diagnose a heart attack.
- BNP or NT-proBNP: a marker of strain on the heart that helps assess heart failure.
- Blood clotting tests: for example INR to monitor warfarin and to prepare for procedures.
- Liver and thyroid function: when your doctor needs to look for other causes of your symptoms or monitor the effects of medicines.
When the Tests Are Done
Laboratory tests can be part of a routine health checkup, the evaluation of symptoms such as chest pain or shortness of breath, preparation before procedures such as catheterization or surgery, and treatment monitoring, for example of cholesterol-lowering medicines, blood thinners, or heart failure medicines. The type of test is tailored to the purpose of the examination and your condition.
Reading Your Results
Each result is listed with a reference range. A result outside the reference range does not always mean illness, and a normal result does not always rule out disease. Some tests, such as troponin, need to be repeated within a few hours to see how the levels change. For this reason, laboratory results should be read by your doctor together with your symptoms, physical examination, and other tests such as an ECG or echocardiography.
02 / Understanding the procedure
When Is This Procedure Considered?
A doctor may consider this procedure in the situations below. The decision is always made after a thorough assessment.
- Routine Health CheckupTo assess heart risk factors such as cholesterol, blood sugar, and kidney function, especially in adults with a family history of heart disease, a smoking habit, or high blood pressure.
- Symptoms Suspected to Come from the HeartChest pain, shortness of breath, swollen legs, or heart palpitations may require tests such as troponin and NT-proBNP as part of the evaluation.
- Preparation Before a ProcedureBefore catheterization, heart surgery, or a test with contrast agent, your doctor needs to know your kidney function, blood clotting, and hemoglobin level.
- Treatment MonitoringMedicines such as blood thinners, cholesterol-lowering drugs, and heart failure medicines need their effects and safety monitored through regular blood tests.
- Monitoring an Existing ConditionIn diabetes, kidney disease, heart failure, or after a heart attack, regular tests help your doctor assess whether treatment targets are being met.
Situations to Consider First
- History of Dizziness or Fainting During Blood DrawsTell the staff beforehand so your blood can be drawn while you lie down.
- Taking Blood Thinners or Having a Clotting DisorderThe puncture site needs to be pressed longer to prevent bleeding or bruising.
- Taking High-Dose Biotin SupplementsBiotin can affect the results of some tests, including troponin and thyroid hormones. Tell your doctor and the staff if you take it.
- Fasting Requirements Not MetIf the test requires fasting but you have already eaten, tell the staff. The test can be rescheduled, or the results can be read with that in mind.
03 / Before the procedure
How Should You Prepare?
Preparation depends on the type of test your doctor orders. The staff will tell you if there are special instructions.
Fast if asked. A fasting blood sugar test requires fasting for about 8 hours. Fasting rules for a lipid profile may differ, so follow the instructions from your doctor or the staff. While fasting, you may still drink plain water.
Regular medicines. In general, keep taking your regular medicines as usual unless your doctor gives other instructions. Bring a list of the medicines and supplements you are taking.
Biotin supplements. Tell your doctor if you take high-dose biotin supplements, because they can affect the results of some tests. Your doctor may ask you to stop the supplement temporarily before the test.
Activity and alcohol. Avoid strenuous exercise and alcohol the day before, because they can affect some results, for example triglycerides and muscle enzymes.
Drink enough water. When your body is well hydrated, your veins are easier to find.
Clothing and documents. Wear a top with loose sleeves that roll up easily. Bring your doctor's referral letter if you have one, and previous test results for comparison.
Unsure about the preparation instructions? Ask our team before the procedure.
04 / During the procedure
How Is the Procedure Done?
The majority of laboratory tests only require a blood sample from a vein in your arm. Drawing the blood takes a few minutes.
Registration and Identity Check
The staff matches your identity with the test request and asks about your preparation, for example whether you have fasted.
Drawing Blood
A tourniquet is tied around your upper arm, the skin is cleaned with antiseptic, and a small needle is inserted into a vein, usually at the inner elbow. The blood is collected in several tubes according to the type of test. You will feel a brief prick.
Pressing the Puncture Site
After the needle is removed, the puncture site is pressed with cotton for a few minutes and then covered with a bandage. Press longer if you take blood thinners.
Other Samples When Needed
For certain tests, your doctor may ask for a urine sample, or a quick finger-prick blood sugar test.
Testing in the Laboratory
The samples are tested with analyzers in the laboratory. Results are rechecked by laboratory staff before they are given to you and your doctor.
05 / Benefits and risks
Benefits and Risks Should Be Discussed Together.
Every medical procedure has benefits and risks. Your doctor will explain both for your situation before the procedure.
Benefits You Can Expect
- Detecting Risk Factors EarlyHigh cholesterol, diabetes, and kidney problems often cause no symptoms. Blood tests help find them before they lead to heart disease.
- Helping Confirm a DiagnosisTests such as troponin and NT-proBNP help your doctor recognize a heart attack and heart failure, together with other tests.
- Monitoring Treatment Results and SafetyRegular tests show whether cholesterol or blood sugar targets are reached and whether medicine doses need adjusting.
- Safer Preparation for ProceduresKnowing your kidney function, blood clotting, and hemoglobin before a procedure helps the team prepare the right steps.
- Quick and SimpleA blood draw only takes a few minutes and one small needle prick.
The benefits of a procedure are not a promise of a cure. Ask how the results will affect your care plan.
Risks You Should Know
- Bruising or Pain at the Puncture SiteThis is common and usually mild, and it goes away on its own within a few days.
- Dizziness or FaintingSome people feel dizzy or faint during or after a blood draw. Tell the staff if this has happened to you before, so your blood can be drawn while you lie down.
- Prolonged BleedingMore likely in people who take blood thinners or have a blood clotting disorder.
- InfectionVery rare, because blood draws use sterile, single-use equipment.
- Repeat Sample CollectionSometimes a sample needs to be taken again, for example if a vein is hard to find or the sample does not meet testing requirements.
- Results That Need Careful InterpretationResults can be affected by food, medicines, supplements, or activity before the test. Results that do not match your condition need to be discussed with your doctor and are sometimes repeated.
Risks can differ from person to person. A full explanation and consent are given after an individual assessment.
06 / After the procedure
What Is Recovery Like?
After your blood is drawn, you can return to your activities right away.
Puncture site. A small bruise at the puncture site is normal and fades within a few days. Avoid lifting heavy objects with that arm for a few hours.
After fasting. If you fasted, eat and drink once the blood draw is finished, then take any delayed regular medicines as advised.
When results are ready. Results of routine tests are usually available on the same day, while special tests may take longer. Urgent tests, such as troponin when a heart attack is suspected, are processed right away.
Discussing the results. Discuss the results with your doctor, including what values outside the reference range mean and when the tests need to be repeated.
Warning signs. Contact the medical team if you have:
- Swelling or bruising that keeps growing at the puncture site
- Bleeding that does not stop after pressing for a few minutes
- Pain, redness, or warmth in the arm that keeps getting worse, or a fever
- Tingling or numbness in the arm that does not go away
Know the Signs That Need Prompt Care.
Follow the team's guidance on warning signs. If severe or sudden symptoms appear after the procedure, go to the nearest emergency department right away or call Heart Attack Center 1500 258.
07 / Team and support
Doctors and Procedure Support
The doctors below are listed for this procedure. Listed by name, not by ranking.
dr. Debby C. Soemitha, Sp.PD
Internal Medicine
Clinical focusDiabetes and Diabetes Complications · Obesity and Metabolic Disease
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Dr. med. dr. Denio A. Ridjab, Sp.JP(K)
Interventional Cardiology
Coronary Intervention Procedures +2 centers
Clinical focusInterventional Cardiology · Coronary Artery Disease
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dr. Khaira U. Yusrie, Sp.PD-KGEH
Gastroenterology & Hepatology
Clinical focusInternal Medicine · Gastroenterology and Hepatology
View Profile08 / Common questions
Before You Plan the Procedure.
Frequently asked questions before laboratory tests for the heart. Instructions specific to your test are given by your doctor or the laboratory staff.
Do I need to fast before laboratory tests?
Not always. A fasting blood sugar test requires fasting for about 8 hours, and some doctors ask for fasting before a lipid profile. Many other tests, such as a complete blood count, kidney function, and troponin, do not require fasting. While fasting, you may still drink plain water. Follow the instructions from your doctor or the laboratory staff for the tests ordered.
Can I take my regular medicines before a blood test?
Usually yes, with a little water, unless your doctor gives other instructions. Some medicines, for example diabetes medicines while fasting, may need to be delayed until after the blood draw so your blood sugar does not drop too low. Ask your doctor if you are unsure, and do not stop heart medicines or blood thinners without your doctor's guidance.
How long does it take to get the results?
Results of routine tests such as a complete blood count, blood sugar, and kidney function are usually available on the same day. Certain tests take longer. In an emergency, for example when a heart attack is suspected, tests such as troponin are processed right away. The staff will tell you the estimated time for your results when you register.
What are troponin and NT-proBNP?
Troponin is a heart muscle protein that enters the blood when the heart muscle is damaged, so it is used to diagnose a heart attack. NT-proBNP is released by the heart when it is working too hard, so it helps assess heart failure. Levels of both are read together with your symptoms, ECG, and other tests, because they can also rise in other conditions such as kidney problems.
My results are outside the reference range. Does that mean I am sick?
Not necessarily. A reference range is the range commonly found in healthy people, and some healthy people have results slightly outside it. Results can also be affected by food, medicines, or activity before the test. Your doctor will assess the results along with your overall condition and decide whether a repeat or further test is needed.
How often should cholesterol and blood sugar be tested?
It depends on your age, risk factors, and previous results. Adults without risk factors are usually tested regularly every few years, while people with diabetes, high cholesterol, or heart disease are usually tested more often, for example every few months while treatment is being adjusted. Your doctor will set a schedule that suits you.
Sources and Medical Review
Translated from the Indonesian edition medically reviewed by dr. Debby C. Soemitha, Sp.PD.
Sources as cited in the Indonesian edition.
- Nordestgaard BG, Langsted A, Mora S, et al. Fasting is not routinely required for determination of a lipid profile: a joint consensus statement from the European Atherosclerosis Society and European Federation of Clinical Chemistry and Laboratory Medicine. Eur Heart J. 2016;37(25):1944-1958.
- Grundy SM, Stone NJ, Bailey AL, et al. 2018 AHA/ACC Guideline on the Management of Blood Cholesterol. Circulation. 2019;139(25):e1082-e1143.
- Thygesen K, Alpert JS, Jaffe AS, et al. Fourth Universal Definition of Myocardial Infarction (2018). Circulation. 2018;138(20):e618-e651.
- Heidenreich PA, Bozkurt B, Aguilar D, et al. 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure. Circulation. 2022;145(18):e895-e1032.
- U.S. Food and Drug Administration. Biotin Interference with Troponin Lab Tests: Assays Subject to Biotin Interference.