Contents

Search

lactose intolerance (milk intolerance)

Etiology: 1) acute gastroenteritis 2) giardia infection Epidemiology: 1) < 25% if white adults 2) > 60% of black adults 3) > 85% of Asian adults 4) develops during childhood or early adulthood, but is rare in children < 3 years of age [5] 5) most common enzyme deficiency worldwide 6) majority of Northern Europeans have the ability to maintain lactase activity & digest lactose throughout life Pathology: 1) lactase deficiency resulting from developmental down-regulation of lactase activity during childhood or early adulthood 2) brush boder lactase is lost 2) degree of lactase deficiency is variable Genetics: - adult form associated with intronic variations in MCM6 upstream from the LCT gene Clinical manifestations: - gastrointestinal symptoms 2-3 hours after ingestion of lactose [6] a) flatulence b) abdominal cramping c) osmotic diarrhea [3] d) bloat e) variability in symptoms - associatied with eating, drinking dairy - improves with fasting - not nocturnal [3] - no weight loss or GI bleed [3] Laboratory: 1) lactose H2 breath test, rarely necessary 2) stool a) anion gap shows osmotic gap b) pH < 6.5 3) MCM6 gene mutation 4) serum 25-OH vitamin D Radiology: 1) abdominal imaging not helpful 2) small bowel series may be helpful if malabsorption is significant Differential diagnosis: 1) irritable bowel syndrome 2) pancreatic insufficiency 3) sprue 4) cystic fibrosis 5) cow's milk protein sensitivity Management: 1) lactose-free diet - lactose-free diet for 2 weeks to confirm diagnosis [2] - lactose-free infant formulas rarely of benefit [5] 2) lactase (Lactaid) before ingestion of milk products - may prevent symptoms in some patients 3) Ca+2 & vitamin D supplementation to prevent osteoporosis* * high risk of vitamin D deficiency (GRS11) [7] * vitamin D supplementation not useful in the absence of vitamin D deficiency

Related

congenital lactase deficiency; hereditary alactasia; disaccharide intolerance 2 cow's milk hypersensitivity (CMH); cow's milk allergy

Specific

lactase deficiency

General

malabsorption food intolerance

Database Correlations

OMIM 223100

References

  1. Ferri's Clinical Advisor, Instant Diagnosis and Treatment, Ferri FF (ed), Mosby, Philadelphia, 2003
  2. Heyman MB for the Committe on Nutrition. Lactose intolerance in infants, children and adolescents. Pediatrics 2006, 118:1279 PMID: 16951027
  3. Medical Knowledge Self Assessment Program (MKSAP) 16, 19 American College of Physicians, Philadelphia 2012, 2021. - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  4. Shaukat A, Levitt MD, Taylor BC et al Systematic review: effective management strategies for lactose intolerance. Ann Intern Med. 2010 Jun 15;152(12):797-803. PMID: 20404262
  5. Sherman AL et al. Lactose-free milk or soy-based formulas do not improve caregivers' distress or perceptions of difficult infant behavior. J Pediatr Gastroenterol Nutr 2015 Jul; 61:119 PMID: 25643020
  6. NEJM Knowledge+ - Jansson-Knodell CL, Krajicek EJ, Savaiano DA, Shin AS. Lactose Intolerance: A Concise Review to Skim the Surface. Mayo Clin Proc. 2020 Jul;95(7):1499-1505. PMID: 32622451 Review.
  7. Geriatric Review Syllabus, 11th edition (GRS11) Harper GM, Lyons WL, Potter JF (eds) American Geriatrics Society, 2022
  8. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) Lactose Intolerance https://www.niddk.nih.gov/health-information/digestive-diseases/lactose-intolerance