Lactase Enzyme Deficiency, Lactose Intolerance

Lactase Enzyme Deficiency

What samples are needed to detect Lactase enzyme deficiency?

1. Most tests available to diagnose lactase enzyme deficiency are performed on stool samples.
2. A blood sample is needed to estimate blood glucose levels.
3. Small intestinal biopsy.
4. Breath test.

How will you define lactase enzyme deficiency?

1. Lactose is a disaccharide and is mainly found in dairy products. Lactose requires the lactase enzyme for digestion. Lactose intolerance develops when the lactase enzyme is deficient; lactose will not break down into glucose and galactose.
2. Lactose intolerance starts in infancy, with S/S of diarrhea, vomiting, and failure to thrive.
3. The patient becomes asymptomatic when lactose is removed from the diet.

What is the epidemiology of Lactase enzyme deficiency?

1. Northern Europeans have normal lactase enzymes, and only 10% to 15% develop lactase enzyme deficiency (Lactose intolerance).
2. The highest incidence is seen in Asian populations, such as Chinese and Japanese.
3. Native Americans:>90% show lactase enzyme deficiency (Lactose intolerance).
4. Jews, African Americans, South Americans, and Eastern Europeans have a lesser deficiency, but still, it is seen in 60% to 70%.

How will you discuss the Pathophysiology of lactase enzyme deficiency?

1. Lactose is a disaccharide and is mainly found in dairy products. Lactose requires the lactase enzyme for digestion. Lactose intolerance develops when the lactase enzyme is deficient; lactose will not break down into glucose and galactose.
2. Lactose is a disaccharide and is mainly found in dairy products.
3. Lactose needs a lactase enzyme for digestion. When the lactase enzyme is deficient, lactose will not be broken down into glucose and galactose, causing lactose intolerance.
4. Lactose intolerance starts in infancy, with diarrhea and vomiting. There is failure to thrive.
5. The patient becomes asymptomatic when lactose is removed from the diet.

What is the mechanism of lactase enzyme deficiency?

1. Lactose sugar is present in:
   1. Milk and milk products.
   2. Ice cream.
   3. Yogurt.
   4. Many types of cheese.
2. In case of a lactase enzyme deficiency, lactose cannot be broken down into glucose and galactose.
3. The brush borders of the small intestine have the enzyme lactase.
4. When there is a genetic abnormality, lactase deficiency, milk sugar cannot be broken down into monosaccharides.

Lactase enzyme deficiency mechanism

What are the types of Lactase enzyme deficiency?

1. Primary, Congenital:
   1. It is the genetic deficiency of the lactase enzyme.
   2. Lactase enzyme appears between 26 and 34 weeks of gestation, with 1/3 activity compared to that of full-term babies.
   3. At 35-38 weeks of gestation, it is around 70%.
   4. Full activity is seen at the 40th week of gestation.
   5. This deficiency appears between ages 3 and 5.
   6. This appears in the newborn.

1. 6. These babies will present with vomiting, diarrhea, malabsorption, and failure to thrive.
   7. This may be seen in premature babies.
2. Secondary (acquired):
3. The  lactase enzyme deficiency is due to:
   1. Gluten sensitivity enteropathy.
   2. Enteritis.
   3. Bacterial growth in the intestine.
   4. Inflammatory bowel disease, such as Crohn’s disease.
   5. Giardia lamblia infestation.
   6. Cystic fibrosis of the pancreas.
4. Other causes of lactase enzyme deficiency are:
   1. There is some degree of lactase enzyme deficiency in adults, but severe deficiency occurs due to the following:
   2. Inflammatory bowel disease.
   3. Short-gut syndrome.
   4. Malabsorption syndrome.
   5. Severe acute gastroenteritis.
   6. Prolonged protein-calorie malnutrition.
   7. Certain antibiotics like neomycin and kanamycin.
5. The small bowel is loaded with lactose when lactose is in the intestine.
6. Intestinal bacteria lead to its fermentation and give rise to:
   1. Gas formation.
   2. The osmotic gradient leads to osmotic diarrhea.

Lactase enzyme deficiency and S/S

What are the clinical features of Lactase enzyme deficiency?

1. There is abdominal floating and distension.
2. Abdominal cramping.
3. There is flatus.
4. Diarrhea.
5. There is bloating.
6. These symptoms are worse after meals.
7. Lactase deficiency in full-term babies or young children is rare.
8. These patients do not thrive.

What are the normal values of Lactase enzyme deficiency?

1. Normal = Glucose change from the normal value = >30 mg/dL (>1.7 mmol/L).
   1. Inconclusive = 20 to 30 mg/dL
   2. Abnormal = <20 mg/dL  (<1.1 mmpl/L) (positive for lactase enzyme deficiency).
2. Breath test (H⁺) = <10 ppm increase from the baseline is abnormal.

How will you diagnose Lactase enzyme deficiency?

What are the Screening tests for lactase deficiency?

1. Stool for pH.
   1. Normal stool pH is 7.0 to 8.0
   2. A stool pH below 6.0 suggests lactase deficiency.
2. Stool sugar at the time of patient symptoms.
   1. Check for reducing sugars, including glucose, using the oxidase method.
   2. The presence of reducing sugars, such as glucose, in the stool suggests lactase enzyme deficiency.

What is the principle of the lactose tolerance test?

1. The principle is similar to that of the glucose tolerance test.
2. The patient is provided with lactose overload.
3. Serum glucose levels are estimated by fasting (before lactose administration) and after administration at 15, 30, 60, and 90 minutes.
4. Normal lactase enzyme activity results in postdose glucose elevation of >20 mg/dL (1.1 mmol/L).
5. Lactose will not be broken down into glucose and galactose in lactase deficiency; plasma glucose levels will not increase.
6. This test is a GTT (glucose tolerance test) to detect a deficiency of the intestinal disaccharidase (lactase) enzyme.
   1. The fasting glucose level is compared with other glucose levels to determine whether it has increased or decreased.
7. What are the precautions for a lactose tolerance test?
   1. Avoid strenuous exercise.
   2. Smoking can increase blood glucose levels.
   3. Don’t allow smoking during the test and 8 hours before the test.
   4. Enterogenous steatorrhea.
   5. Patients with diabetes mellitus may have blood glucose levels increased by 20 mg/dL despite lactase deficiency.
   6. The patient must fast 8 to 12 hours before the test.
   7. The patient should not eat dark bread, beans, sugars, or high-fiber food within 24 hours of the test.
   8. Don’t allow gum chewing.
   9. Don’t allow antibiotic therapy 2 weeks before the test.
8. Procedure for lactose tolerance test:
   1. After an overnight fast.
   2. Give 50 grams of lactose mixed with 200 mL of water. (1 to 2 grams lactose/kg of body weight).
   3. You can give this with flavored fluid or soft drinks.
   4. Draw the blood sample at 0 (fasting), 30, 60, and 90-minute intervals. (Some labs check fasting glucose at 30, 60, 90, and 120 minutes).
   5. Some labs check galactose instead of glucose levels.
9. Interpretations:
   1. There is flat lactose tolerance, meaning no rise in glucose levels.
   2. At normal lactase enzyme level, glucose elevation is >20 mg/dL (1.1 mmol/L) over baseline.
   3. Lactose in the urine produces a positive test for reducing sugars but is negative by the glucose oxidase method.
   4. Take a single blood sample 40 minutes after the test and check the galactose level.

Hydrogen breath test:

1. It is considered the most accurate of the tolerance tests.
2. It is based on the expiratory hydrogen in the breath.
3. Oral Lactose is given to the patient, and breath hydrogen is retested at 30, 60, and 2- to 4-hour intervals.
4. Lactose deficiency results in the deposition of excess lactose in the colon, where bacterial fermentation produces excess hydrogen, which is exhaled through the lungs.

Small intestinal biopsy:

1. It can be done by endoscopy to evaluate the contents of the lactose enzyme in the tissue.
2. Tissue biopsy has additional advantages for differentiating sprue.

How will you summarize the diagnostic tests for lactase enzyme deficiency?

1. Lactose intolerance test.
2. Hydrogen breath test.
3. Small intestinal biopsy with tissue assay of lactase enzyme.

Questions and answers: