Overview

Blood test results show how the body is working by measuring blood cells, sugar, fats, vitamins, and substances linked to the kidneys, liver, and thyroid. Each result appears next to a reference range, which is the range seen in most healthy people.

Reference ranges vary between laboratories and can differ by age, sex, and during pregnancy. A result slightly outside the range is not always a problem, and a normal result does not rule out every condition. A doctor interprets results together with symptoms, medical history, and earlier tests, so numbers alone should not guide decisions.

Common Blood Tests

• Complete blood count (CBC): hemoglobin, red cells, white cells, and platelets
• Lipid profile: total cholesterol, LDL ("bad") and HDL ("good") cholesterol, and triglycerides
• Blood sugar: fasting glucose and HbA1c, which reflects average sugar over about 3 months
• Kidney function: creatinine, eGFR, urea, and salts such as sodium and potassium
• Liver function: ALT, AST, alkaline phosphatase, bilirubin, and albumin
• Vitamin D, plus iron studies including ferritin, the body's iron store
• TSH, the main first test for thyroid function

What Abnormal Results Can Mean

• Low hemoglobin: anemia; abnormal white cell or platelet counts need a doctor's review
• High LDL or triglycerides: a higher risk of heart disease and stroke
• High fasting glucose or HbA1c: possible prediabetes or diabetes
• High creatinine or low eGFR: reduced kidney function or dehydration
• High ALT or AST: liver irritation, often from fatty liver, medicines, or viral hepatitis
• Low ferritin or vitamin D: low stores that may need supplements under medical advice
• High TSH suggests an underactive thyroid; low TSH suggests an overactive thyroid

Preparing for a Blood Test

• Fasting for 8–12 hours only when the doctor or lab asks, usually for fasting glucose; water is allowed
• Drinking water beforehand, which also makes drawing blood easier
• Telling the doctor about all medicines and supplements
• Pausing biotin (a hair and nail supplement) for a few days before thyroid and some hormone tests, if the doctor agrees
• Avoiding hard exercise the day before, since it can briefly raise some muscle and liver results
• Bringing earlier results to compare changes over time

When to See a Doctor

• To review any result flagged high or low, even without symptoms
• When results change clearly from earlier tests
• Before starting iron, vitamin D, or other supplements based on a result
• For repeat testing and follow-up when the doctor recommends it
• Seek emergency care for chest pain, fainting, severe weakness, shortness of breath, or unusual bleeding, whatever the results show

The Laboratory and Internal Medicine departments at AlHayat Medical Center perform blood tests and explain what the results mean.

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