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The syndrome of Lactose intolerance (hypolactasia) is caused by the inability of the body to digest disaccharide lactose, contained in milk products, partially or completely, into glucose and galactose.
Biochemical reason of lactose intolerance is missing or to low concentration of the enzyme lactase-phlorizin hydrolase (LPH), which processes lactose in small intestines. Lactose remains in intestine and becomes processed by microbes, resulting malabsorption with gas bloat, flatulance, diarrhea and abdominal pain. Additional there are a plenty of unspecific symptoms like headache, state of exhaustion and cardiovascular problems.
Forms of lactose intolerance
There exists three different forms of lactose intolerance:
- Acquired lactase deficiency is the most common. Here production of lactase decreases with aging and can stop completely (physiological lactase deficiency)
- Primary or neonatal lactase deficiency is very rare and means that there is no lactase production from birth on.
- Secondary lactase deficiency rises as a result of gastrointestinal diseases like celiac disease (see AID kit RDB2065E) or Morbus Crohn. Secondary lactase deficiency may improve, when main disease heals and lactase concentration rises again.
About 50% of world population suffer from a more or less manifested lactose intolerance. While frequency in Europe and Northern America lies between 10 and 20%, Asia and Africa in parts is affected up to 100%.
Up to 25% of the children with total lack of alpha-1-antitrypsin (homozygous
PiZ mutation) develop a cirrhosis of the liver, while about 75% of
all adults concerned develop obstructive lung diseases.
PiZ is by far the most frequent of the deficiency alleles with clinical
significance. The also frequent PiS allele seems to be relevant only
in combination with the PiZ allele. Carriers of PiS alone normally
do not get ill.
Heterozygous carriers of PiMZ or PiSZ normally are clinically inconspicious
or, with the exception of smokers, only develop a mild form of the
illness. Heterozygous carriers who smoke in most cases develop chronical
obstructive lung diseases comparable to the symptoms seen in homozygous
non-smoking carriers.
The diagnosis is effected by determining the level of alpha-1-antitrypsin
in the blood. A significantly diminished concentration of this protein
points to homozygositiy of the defect. Heterozygous carriers of the
defect mutation show concentrations in the lower region of the normal
range. Since alpha-1-antitrypsin is an acute phase protein, even heterozygous
carriers may show a slightly increased level during infections or
under therapy with estrogens or other steroids. The determination
of the alpha-1-antitrypsin level in the blood therefore is unsuitable
for the detection of heterozygous carriers. Only the typing of the
alpha-1-antitrypsin alleles allows a diagnostic statement.
With the alpha-1-antitrypsin assay from AID homo- and heterozygous
carriers can be unmistakably detected and differentiated. Other, mostly
irrelevant alleles are not taken into account.
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