Galactosemia Heel Prick

Pregnancy

Report in 72Hrs

At Home

No Fasting Required

Details

Newborn screening for galactose metabolism defect.

₹296₹423

30% OFF

Galactosemia Heel Prick Test - Comprehensive Medical Guide

Why is it done?
- Test Purpose: The galactosemia heel prick test screens for galactosemia, a rare inherited metabolic disorder that prevents the body from properly metabolizing galactose (a simple sugar found in milk and dairy products) into glucose.
- Primary Indications: Universal newborn screening performed within 24-48 hours of birth as part of routine metabolic screening to identify three forms of galactosemia (classic galactosemia, galactokinase deficiency, and UDP-galactose-4-epimerase deficiency).
- Typical Timing: Performed as part of newborn metabolic screening programs in most developed countries, typically 24-48 hours after birth, before hospital discharge or at first pediatric visit. May be repeated at 1-2 weeks of life for confirmation if initial screening is borderline or positive.
- Clinical Significance: Early detection allows for immediate dietary intervention (lactose-free formula) to prevent severe complications including intellectual disability, cataracts, liver dysfunction, and ovarian failure in females.
Normal Range
- Normal Values - Galactose Levels: Less than 12 mg/dL (0.67 mmol/L) of blood galactose is considered normal. Reference ranges may vary slightly between laboratories and screening methods.
- Galactose-1-Phosphate Uridyltransferase (GALT) Activity: Normal enzyme activity is typically 25-37 U/mL (units/milliliter of red blood cells). Low or absent activity indicates galactosemia.
- Interpretation of Results: • Normal (Negative): Galactose < 12 mg/dL AND normal GALT enzyme activity; no galactosemia detected • Borderline/Screen Positive: Elevated galactose (12-20 mg/dL) or mildly reduced GALT activity; requires repeat testing • Positive (Abnormal): Galactose > 20 mg/dL AND/OR significantly reduced or absent GALT enzyme activity; indicates galactosemia
- Units of Measurement: Galactose measured in mg/dL or mmol/L; GALT enzyme activity measured in U/mL; galactose-1-phosphate measured in mg/dL or μmol/L.
- Clinical Interpretation: Normal results indicate the newborn does not have galactosemia and can safely consume breast milk or standard formula. Abnormal results require confirmatory testing and immediate pediatric/metabolic specialist consultation.
Interpretation
- Classic Galactosemia (Severe Form): Characterized by severely elevated galactose (>30 mg/dL), markedly reduced or absent GALT enzyme activity (<5% of normal), and elevated galactose-1-phosphate (>10 mg/dL). Represents approximately 90% of galactosemia cases. Requires immediate dietary intervention to prevent permanent neurological damage and other complications.
- Galactokinase Deficiency: Elevated galactose levels with normal GALT enzyme activity and normal galactose-1-phosphate levels. Represents 10-15% of cases. Generally has better prognosis with risk primarily of infantile cataracts; however, dietary galactose restriction still recommended.
- UDP-Galactose-4-Epimerase Deficiency: Variable elevations in galactose and galactose-1-phosphate with specifically reduced epimerase activity. Classified as peripheral (benign) or generalized (more severe). Peripheral form carries better prognosis; generalized form requires dietary management similar to classic galactosemia.
- False Positives: Can occur in newborns with high total serum bilirubin, hemolysis, sepsis, or those receiving blood transfusions within 48 hours of screening. Prematurity or early sampling (<24 hours) may elevate galactose levels without true disease.
- Factors Affecting Results: Timing of sample collection (earlier collection may yield false positives), maternal blood contamination in heel prick sample, infection or illness in newborn, dietary intake (exclusive breastfeeding may show lower galactose than formula-fed infants), and laboratory methodology differences.
- Clinical Significance of Patterns: Isolated elevated galactose may indicate galactokinase deficiency or epimerase deficiency. Combined elevation of galactose and galactose-1-phosphate with low GALT activity indicates classic galactosemia (most severe form). Repeat testing pattern showing persistence indicates true disease; normalization suggests false positive.
Associated Organs
- Primary Organ Systems Involved: • Central Nervous System: Brain and peripheral nerves are most severely affected; galactose accumulation causes intellectual disability, developmental delay, hypotonia, and seizures if untreated • Hepatic System: Liver dysfunction including cirrhosis, hepatomegaly, and liver failure • Ocular System: Cataracts (infantile cataracts typically appear by 4-6 weeks of life in untreated classic galactosemia) • Reproductive System: Ovarian failure and primary amenorrhea in females; subfertility in males • Metabolic System: Abnormal glucose metabolism and hypoglycemia risk
- Medical Conditions Associated with Abnormal Results: Galactosemia (all three enzymatic variants), neonatal sepsis (may transiently elevate galactose), hemolytic disease of the newborn, liver disease, and sepsis-related metabolic derangements.
- Diseases Detected or Diagnosed: Galactosemia (classic, galactokinase deficiency, and epimerase deficiency variants); secondary metabolic complications related to galactose accumulation.
- Potential Complications if Untreated - Neurological: Intellectual disability (IQ often 40-60 if untreated), developmental delay, speech and language disorders, ataxia, tremor, seizures, nystagmus, and movement disorders progressing to severe disability.
- Potential Complications if Untreated - Ophthalmologic: Infantile cataracts with potential for blindness if not managed; cataracts may be partially reversible if galactose restriction initiated early.
- Potential Complications if Untreated - Hepatic: Neonatal cholestasis, hepatomegaly, cirrhosis, liver failure, and hepatic encephalopathy progressing to fatal liver disease within first years of life.
- Potential Complications if Untreated - Reproductive: Ovarian failure with premature menopause in females typically by age 20-30 years; reduced fertility and subfertility in males.
Follow-up Tests
- Confirmatory Testing - Plasma Galactose Level: Quantitative measurement of plasma galactose to confirm and quantify elevation; normal <5 mg/dL, abnormal >10 mg/dL in newborns.
- Confirmatory Testing - Red Blood Cell GALT Enzyme Assay: Quantitative measurement of galactose-1-phosphate uridyltransferase enzyme activity in red blood cells; <5% of normal activity confirms classic galactosemia.
- Confirmatory Testing - Galactose-1-Phosphate Uridyltransferase Assay: Specific enzyme testing to differentiate between different galactosemia variants; galactokinase and epimerase-specific assays may be performed.
- Confirmatory Testing - Urinary Galactitol and Galactose: Elevated urinary galactitol and galactose support diagnosis of galactosemia; galactitol in urine is a marker of galactose accumulation.
- Genetic Testing - DNA Sequencing: Mutation analysis of the GALT, GALK1, and GALE genes to confirm enzymatic defect and identify specific mutations; particularly useful for definitive diagnosis and genetic counseling.
- Ophthalmologic Evaluation: Slit-lamp examination and dilated eye examination within 2 weeks of positive screening to assess for cataracts and establish baseline; repeat examinations as part of long-term follow-up.
- Hepatic Assessment - Liver Function Tests: Alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, and albumin to assess for hepatic involvement; perform initially and periodically during follow-up.
- Hepatic Assessment - Hepatic Ultrasound: Imaging to assess liver echotexture, exclude cirrhosis, and monitor for structural changes; particularly important if clinical or biochemical evidence of hepatic dysfunction.
- Neuroimaging - Cranial MRI: Magnetic resonance imaging to assess for white matter abnormalities, neuronal migration disorders, and baseline neurological status; indicated if clinical neurological concerns.
- Developmental Assessment: Formal developmental screening using validated tools (Bayley Scales, Denver Developmental Screening Test) at regular intervals (3 months, 6 months, 12 months, then annually) to monitor neurological development.
- Monitoring Frequency - Immediate/Acute Phase: Confirmatory testing within 5-7 days of positive screening; clinical assessment and laboratory monitoring weekly for first month on dietary therapy.
- Monitoring Frequency - Ongoing Management: Monthly metabolic and clinical assessment for first 3-6 months; quarterly assessment during first year of life; biannual assessment thereafter. Plasma galactose-1-phosphate levels monitored routinely (goal <5 mg/dL) as primary indicator of dietary compliance.
- Complementary Tests - Newborn Screening Panel: Other components of newborn metabolic screening (screening for phenylketonuria, congenital hypothyroidism, sickle cell disease, etc.) should be reviewed as children may have multiple metabolic or genetic conditions.
- Long-term Follow-up Testing - Reproductive Function: In females, anti-mullerian hormone (AMH) levels and reproductive hormone panels (FSH, LH) to monitor for ovarian reserve loss; ovarian ultrasound to assess ovarian volume and follicle count.
- Specialist Consultations: Metabolic specialist for ongoing management and dietary optimization; pediatric ophthalmologist for cataract monitoring; pediatric neurologist if neurological symptoms develop; pediatric hepatologist if hepatic dysfunction evident; reproductive endocrinologist for adolescent/adult reproductive assessment.
Fasting Required?
- Fasting Requirement: No - Fasting is NOT required for the galactosemia heel prick test. The test is performed as part of universal newborn screening and does not require dietary preparation or fasting.
- Timing of Sample Collection: Test should be collected 24-48 hours after birth (between 2nd and 3rd day of life). Collection before 24 hours may result in falsely elevated galactose levels due to normal physiological adaptation; collection after 48 hours may result in false negatives.
- Infant Feeding Status: No specific feeding status required prior to testing. Test can be performed whether infant is breastfed, formula-fed, or combination fed. Breastfed infants may have slightly different galactose levels than formula-fed infants, but this does not affect test validity or interpretation.
- Special Patient Preparation: Newborn should be gently warmed to promote blood flow before heel prick; first drop of blood should be wiped away, and subsequent drops collected on special filter paper cards. Heel prick should be performed on lateral or medial heel surface, not central area.
- Medications: No medications need to be withheld or avoided prior to this screening test. However, inform healthcare provider of any medications infant has received (particularly antibiotics or transfusions) as these may affect test interpretation.
- Special Instructions - Sample Handling: Filter paper cards must be labeled with infant name, date/time of collection, and date of birth. Cards should air dry for at least 3 hours in horizontal position before transport. Avoid excessive pressure when placing blood on filter paper.
- Special Instructions - Repeat Testing: If initial screening is borderline or positive, repeat testing must be performed at 1-2 weeks of life using venous blood sample for confirmation. Inform parents that positive screening requires follow-up testing but does not necessarily confirm diagnosis.
- Avoid Common Errors: Contamination of specimen with maternal blood (which may interfere with test results); collection before 24 hours of life; improper sample collection technique; inadequate blood spots on filter paper; delays in laboratory processing; or failure to notify parents of abnormal results promptly.
- Parental Communication: Parents should be informed about the newborn screening program and reasons for testing. Explain that positive results require follow-up testing but may represent false positive. Ensure clear communication regarding recommended follow-up appointments and dietary changes if galactosemia is confirmed.

How our test process works!