Lactose Intolerance Disease

BASICS

DESCRIPTION

Inability to digest lactose (the primary sugar in milk) into its constituents, glucose and galactose, due to low levels of lactase enzyme in the brush border of the duodenum

Congenital lactose intolerance – very rare
Primary lactose intolerance – common in adults in whom a low level of lactase has developed after childhood. Symptoms are experienced after consumption of milk. Intolerance varies with amount of lactose consumed.
Secondary lactose intolerance – inability to digest lactose caused by any condition injuring the intestinal mucosa (e.g., diarrhea) or a reduction of available mucosal surface (e.g., resection). This is usually transient, with the duration of the intolerance determined by the nature and course of the primary condition.
50% or more of infants with acute or chronic diarrhea have lactose intolerance, especially with rotavirus disease. Also fairly common with giardiasis and ascariasis, inflammatory bowel disease, and the AIDS malabsorption syndrome.
Lactose malabsorption – inability to absorb lactose. This does not necessarily parallel lactose intolerance.
System(s) affected: Gastrointestinal, Endocrine/Metabolic
Genetics: Unknown
Incidence/Prevalence in USA:
- Primary lactose intolerance – varies according to race. 75–90% of American Indians, blacks, Asians, Mediterraneans, and Jews; less than 5% of descendants of Northern and Central Europeans.
- Secondary lactose intolerance – 50% or more of infants with acute or chronic diarrheal disease have lactose intolerance, especially with rotavirus disease. Also fairly common with giardiasis and ascariasis, inflammatory bowel disease, and the AIDS malabsorptive syndrome.
Predominant age:
- Primary – teenage and adult
- Secondary – depends on the underlying condition
Predominant sex: Male = Female. However, 44% of lactose intolerant women will regain the ability to digest lactose during pregnancy.

SIGNS AND SYMPTOMS

Bloating
Cramping
Abdominal discomfort
Diarrhea or loose stools
Flatulence
Rumbling (borborygmi)
Only one-third to one-fifth of people with lactose malabsorption will develop symptoms. Degree of symptoms varies with lactose load and with other foods consumed at the same time.
In children – vomiting is common; frothy, acid stools; malnutrition can occur

CAUSES

Primary lactose intolerance – normal decline in lactase activity in the intestinal mucosa after weaning, which is genetically controlled and permanent
Secondary lactose intolerance – associated with gastroenteritis in children
Also nontropical and tropical sprue, regional enteritis, abetalipoproteinemia, cystic fibrosis, ulcerative colitis, immunoglobulin deficiencies in both adults and children

RISK FACTORS

Race
Age

DIAGNOSIS

LABORATORY

Low fecal pH and reducing substances only valid when stools are collected fresh and assayed immediately. Fairly insensitive.

Drugs that may alter lab results: None
Disorders that may alter lab results: None

PATHOLOGICAL FINDINGS

Lactase deficiency in intestinal mucosa - may be patchy or focal. Rarely used in clinical practice.

SPECIAL TESTS

Lactose breath hydrogen test – especially in children
Lactose absorption test – alternative to lactose breath hydrogen test in adults

IMAGING

None

DIAGNOSTIC PROCEDURES

Small bowel biopsy for assay of lactase activity - may be normal if deficiency is focal or patchy (not readily available and usually not necessary)

TREATMENT

APPROPRIATE HEALTH CARE

Outpatient except severe cases of malnutrition

GENERAL MEASURES

No disease specific measures

SURGICAL MEASURES

N/A

ACTIVITY

Full activity

DIET

Reduce or restrict dietary lactose to control symptoms
Yogurt and fermented products such as hard cheeses are tolerated better than milk
Supplement calcium in the form of calcium carbonate
Commercially available "lactase" preparations (Lactaid or Lactrase) are effective in reducing symptoms in many people
Prehydrolyzed milk (Lactaid) is available and effective

PATIENT EDUCATION

Patients must read labels on commercial products since milk-sugar is used in many products and may cause symptoms
Lactose intolerant patients may tolerate whole milk or chocolate milk better than skim
Lactose consumed with other food products is better tolerated than when it is consumed alone
Primary lactase deficiency is permanent; secondary lactose intolerance is usually temporary, though it may persist for several months after the inciting disease has been cured

FOLLOW UP

PREVENTION/AVOIDANCE

Avoidance of lactose in large quantities will relieve symptoms. Patients can learn what level of lactose is tolerable in their diet.

POSSIBLE COMPLICATIONS

Calcium deficiency

EXPECTED COURSE AND PROGNOSIS

Normal life expectancy
Symptoms can be controlled

MISCELLANEOUS

ASSOCIATED CONDITIONS

Tropical or nontropical sprue
Giardiasis
Immunoglobulin deficiencies
Crohn's disease
Cystic fibrosis

AGE-RELATED FACTORS

Pediatric:

Primary lactose intolerance occurs after weaning – usually beginning in late childhood
Breast milk contains a large quantity of lactose but does not seem to worsen diarrhea associated with viral or bacterial diseases
Lactose-free formulas are available

Geriatric: No increase in lactose intolerance in this age group
Others: Secondary lactose intolerance can begin at any age

PREGNANCY

44% of lactose intolerant women will be able to tolerate lactose while pregnant

OTHER NOTES

N/A

ABBREVIATIONS

N/A

Clinical Investigations

ROLE OF HOMOEOPATHY

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