History and exam
Key diagnostic factors
common
African-American, Native American, Asian, Hispanic, or Jewish ethnicity
Primary hypolactasia is far more common in nonwhite people than white people, except for those of Jewish ancestry, due to higher frequencies of lactase nonpersistence in these populations.[2][9][10][11]
There is anecdotal evidence to suggest that individuals whose ancestors consumed large amounts of dairy products over very long periods have lactase persistence due to mutations, while those whose ancestors consumed small amounts of dairy products have lactase nonpersistence and develop lactose intolerance at variable ages.
adolescence and early adulthood
Typical age group of most patients presenting with primary lactase deficiency. Onset of intolerance symptoms is typically subtle and progressive over many years.
family history of lactase deficiency
A positive family history is common.
enteritis/gastroenteritis
Common cause of secondary disease, especially in individuals from developing countries.
comorbid predisposing disease
HIV enteropathy, celiac disease, tropical sprue, Whipple disease, carcinoid syndrome, cystic fibrosis, diabetic gastropathy, kwashiorkor, Zollinger-Ellison syndrome, chemotherapy treatment, colchicine use (for familial Mediterranean fever), and radiation enteritis can all cause secondary disease.
history of irritable bowel syndrome diagnosis
symptoms after ingestion of dairy products
Symptoms typically develop between a few minutes and a couple of hours after ingestion of lactose from dairy and nondairy products. Symptoms can take up to 12 hours to develop in some patients.
diarrhea
Stools are usually explosive, bulky, frothy, and watery after ingestion of lactose-containing products.
More pronounced with secondary disease than primary lactase deficiency.
distention
Due to colonic fermentation of unabsorbed lactose with production of hydrogen, methane, and carbon dioxide, with increased intracolonic pressure.
lethargy
May indicate lactase deficiency when accompanied by typical gastrointestinal symptoms.
Such associated systemic symptoms are more common in adults.
mouth ulceration
May indicate lactase deficiency when accompanied by typical gastrointestinal symptoms. About a quarter of these patients have mouth ulcers.
Such associated systemic symptoms are more common in adults.
May also be present in patients with secondary disease (e.g., due to kwashiorkor, chemotherapy).
headache
May indicate lactase deficiency when accompanied by typical gastrointestinal symptoms.
Such associated systemic symptoms are more common in adults.
poor short-term memory
May indicate lactase deficiency when accompanied by typical gastrointestinal symptoms.
Such associated systemic symptoms are more common in adults.
poor concentration
May indicate lactase deficiency when accompanied by typical gastrointestinal symptoms.
Such associated systemic symptoms are more common in adults.
muscle/joint pain
May indicate lactase deficiency when accompanied by typical gastrointestinal symptoms.
Such associated systemic symptoms are more common in adults.
Joint pain and arthritis may also be present in patients with secondary disease due to Whipple disease.
atopic dermatitis
May indicate lactase deficiency when accompanied by typical gastrointestinal symptoms.
Such associated systemic symptoms are more common in adults.
faltering growth
Malabsorption occurs due to diarrhea and is characteristic of congenital lactase deficiency.
Other diagnostic factors
common
abdominal pain/discomfort
May be cramping in nature. Usually localized to the periumbilical area.
Due to colonic fermentation of unabsorbed lactose with production of hydrogen, methane, and carbon dioxide, with increased intracolonic pressure.
borborygmi
Patient may describe rumbling in the abdomen.
flatulence
May contribute to improvement of symptoms.
skin rashes
May indicate the presence of secondary lactase deficiency; for example, in patients with HIV enteropathy, colchicine use (for familial Mediterranean fever), and radiation enteritis.
palpitations
Arrhythmias may indicate lactase deficiency when accompanied by typical gastrointestinal symptoms.
Such associated systemic symptoms are more common in adults.
May also be present in patients with secondary disease due to carcinoid syndrome.
history of asthma
May indicate lactase deficiency when accompanied by typical gastrointestinal symptoms.
Such associated systemic symptoms are more common in adults.
uncommon
history of peptic ulcer disease
May be present in patients with secondary disease due to Zollinger-Ellison syndrome.
history of gastroesophageal reflux disorder
May be present in patients with secondary disease due to Zollinger-Ellison syndrome.
nausea
Often seen in adolescent patients.
vomiting
Often seen in adolescent patients.
constipation
Almost 25% of patients have constipation.[37]
pallor
May be present in patients with anemia due to secondary disease, (e.g., due to eosinophilic enteritis, celiac disease).
steatorrhea
May be present in patients with secondary disease, (e.g., due to tropical sprue, Zollinger-Ellison syndrome).
weight loss
May be present in patients with secondary disease, (e.g., due to eosinophilic enteritis, celiac disease, tropical sprue).
short stature
May be present in patients with secondary disease due to celiac disease.
progressive disability
May be present in patients with secondary disease due to cystic fibrosis.
flushing
May be present in patients with secondary disease due to carcinoid syndrome.
sensory loss
May be present in patients with secondary disease due to diabetic gastropathy.
edema
May be present in patients with secondary disease due to kwashiorkor.
hair loss
May be present in patients with secondary disease; for example, chemotherapy use, colchicine use (for familial Mediterranean fever), radiation enteritis.
Risk factors
strong
African-American, Native American, Asian, Hispanic, or Jewish ethnicity
Primary hypolactasia is far more common in nonwhite people than white people, except for those of Jewish ancestry, due to higher frequencies of lactase nonpersistence in these populations.[2][9][10][11]
There is anecdotal evidence to suggest that individuals whose ancestors consumed large amounts of dairy products over very long periods have lactase persistence due to mutations, while those whose ancestors consumed small amounts of dairy products have lactase nonpersistence and develop lactose intolerance at variable ages.
adolescence and early adulthood
Typical age group of most patients presenting with primary lactase deficiency. Onset of intolerance symptoms is typically subtle and progressive over many years.
family history of lactase deficiency
A positive family history is common.
enteritis/gastroenteritis
Common cause of secondary disease, especially in individuals from developing countries.
comorbid predisposing disease
HIV enteropathy, celiac disease, tropical sprue, Whipple disease, carcinoid syndrome, cystic fibrosis, diabetic gastropathy, kwashiorkor, Zollinger-Ellison syndrome, chemotherapy treatment, colchicine use (for familial Mediterranean fever), and radiation enteritis can all cause secondary disease.
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