Complete Guide to Medical Lab Tests, Screening Tests and Imaging Investigations
Maintaining your health depends largely on prevention. Laboratory tests, tumor markers, screening tests and modern imaging investigations enable the early detection of diseases and reduce the risk of severe complications.
1. Essential Laboratory Tests
1.1 Complete Blood Count
The complete blood count measures the main components of the blood:
- Red blood cells (erythrocytes) – indicate anemia or dehydration
- White blood cells (leukocytes) – elevated in infections, inflammation or hematological diseases
- Platelets – essential for clotting
Recommendation: A routine test, or whenever symptoms such as fatigue, paleness, fever or bleeding appear.
1.2 Glycemic Profile: Blood Glucose + HbA1c
- Blood glucose – identifies elevated blood sugar levels
- HbA1c – shows how blood sugar has been controlled over the past 3 months
1.3 Lipid Profile
Includes: total cholesterol, LDL, HDL, triglycerides.
Elevated values signal cardiovascular risk and the need for lifestyle changes.
1.4 Liver Function Tests
AST (TGO), ALT (TGP), GGT, bilirubin, alkaline phosphatase
These values indicate the health of the liver and may signal steatosis, hepatitis, or drug-related or alcohol-related toxicity.
1.5 Kidney Function
Urea, creatinine, eGFR
Assesses blood filtration and kidney health; important for people with hypertension or diabetes and for elderly patients.
1.6 Hormone Tests
Thyroid function
Adrenal function
Endocrine assessment, fertility
Menstrual disorders
1.7 Urinalysis
Detects urinary tract infections, blood in the urine, pathological proteins or signs of kidney disease.
2. Important Tumor Markers
Tumor markers are substances produced by the body in certain oncological conditions. They do NOT establish a diagnosis on their own, but they are useful in:
- Monitoring treatment
- Detecting recurrences
- Guiding imaging investigations
CEA (Carcinoembryonic Antigen)
Colorectal cancer
May also rise with smoking, inflammation or liver disease
CA 19-9
Pancreatic and biliary cancer
An important marker for diagnosis and monitoring
AFP (Alpha-fetoprotein)
Liver cancer (HCC)
Also elevated in germ cell tumors
CA 125
Ovarian cancer
May also rise with endometriosis, pelvic infections or ascites
PSA (Prostate-Specific Antigen)
Prostate cancer screening
Interpretation requires clinical correlation
CA 15-3 and CA 27-29
Monitoring breast cancer
Used in treatment follow-up
β-hCG
Germ cell tumors
Testicular or ovarian
3. Recommended Screening Tests
Screening saves lives by detecting diseases at early stages, even before symptoms appear.
3.1 FIT Test (fecal occult blood)
- • Detects microscopic bleeding from the colon
- • Recommended annually or every 2 years
- • Useful for the prevention of colorectal cancer
3.2 Pap Test and HPV
- • Prevention of cervical cancer
- • Detects precancerous lesions
- • Recommended for women from the age of 21–25
3.3 Mammography
- • Routine screening for breast cancer
- • Recommended annually after the age of 40–45
3.4 Screening Colonoscopy
- • The most accurate method for the prevention of colorectal cancer
- • Allows polyps to be removed during the same session
4. Colonoscopy
Colonoscopy is the endoscopic investigation of the colon, essential in diagnosis and prevention.
Indications
- • Blood in the stool
- • Changes in bowel movements
- • Iron-deficiency anemia
- • Persistent abdominal pain
- • Screening after the age of 45–50
What it can detect
- • Colorectal polyps
- • Colorectal cancer
- • Diverticulosis
- • Inflammatory bowel disease (Crohn's, ulcerative colitis)
Colonoscopy is the only investigation that allows both diagnosis and treatment (polypectomy, hemostasis, dilations).
5. Gastroscopy
Gastroscopy examines the esophagus, stomach and duodenum.
Indications
- • Heartburn and reflux
- • Epigastric pain
- • Suspected gastric ulcer
- • Persistent nausea, vomiting
- • Weight loss
- • Iron-deficiency anemia
What it can identify
- • Gastritis and Helicobacter pylori
- • Esophagitis, reflux disease
- • Ulcers
- • Tumors and polyps
- • Gastrointestinal bleeding
6. Computed Tomography (CT)
CT is a fast imaging investigation that uses X-rays to create detailed images of the internal organs.
Indications
- • Trauma
- • Tumor assessment
- • Infections, abdominal inflammation
- • Lung pathology
- • Cancer staging
Advantages
- High examination speed
- Very useful in emergencies
- Precise images of bones and internal organs
CT is often the first-line investigation in acute pathology.
7. Magnetic Resonance Imaging (MRI)
MRI uses a magnetic field, NOT radiation, and is sometimes superior to CT for soft tissues.
Indications
- • Brain or spinal tumors
- • Joint pain, ligament injuries
- • Assessment of the rectum in colorectal cancer
- • Liver and pancreatic conditions
- • Complex cardiovascular investigations
Advantages
- No radiation
- Excellent tissue contrast
- Useful in neurology, cardiology and oncology
8. Stomas: Types and Common Problems
A stoma is a surgically created connection between an internal organ and the skin, allowing the elimination of intestinal or urinary contents.
Types of Stomas
Colostomy
Exteriorization of the colon. More solid stool. Can be temporary or permanent.
Ileostomy
Exteriorization of the ileum. Liquid or semi-liquid stool. Requires hydration and electrolyte supplementation.
Urostomy
Urinary diversion through a segment of intestine. Frequently used after cystectomy.
Possible Stoma Problems
Skin irritation
Caused by leaks or incorrect fitting of the appliance.
Parastomal hernia
A bulge around the stoma; occurs mainly in overweight patients.
Stoma prolapse
A longer portion of intestine protrudes outward.
Retraction
The stoma sinks below skin level, making it difficult to seal the pouch.
Obstruction
More common in ileostomies, caused by indigestible foods.
Local infections
Require prompt treatment to prevent complications.
Patients with a stoma benefit from therapeutic education, a stoma care nurse consultation and periodic follow-up with the surgeon.
Conclusion
Early diagnosis with the help of laboratory tests, tumor markers, screening and modern imaging investigations is the foundation of preventive medicine. Colonoscopy, gastroscopy, CT and MRI are essential tools in the early identification of digestive, oncological and internal diseases.
In addition, patients with a stoma need specialized support in order to enjoy the best possible quality of life.