How Diseases that Cause
Hair Loss are Diagnosed
Introduction
to hair loss diseases and diagnostic procedures
There
are many types of hair loss diseases. Diagnosis depends
on which type of diseases. In practice, most doctors
are likely to come across only about 20 types of hair
loss diseases throughout their careers. Just four of
these account for 95% of the types of hair loss a doctor
sees. These are pattern baldness (hereditary),
telogen effluvium (stress related), chemical overprocessing
and alopecia areata (spot baldness - hereditary).
Normally
during a medical examination, the spots which type of
hair loss diseases the patient is suffering from and
then prescribe treatments or hair care remedies. Questioning
is the most common method of providing information or
diagnosis. Diagnostic techniques such as a hair pluck
test can also help to identify diseases that cause hair
loss.
Questioning
for information
The first
stage of diagnosis involves deciding whether the diseases
that cause hair loss are congenital, genetically inherited,
or acquired. Congenital hair loss diseases are present
from birth while a genetically inherited disease develops
later in life as a result of inherited genes. Acquired
diseases are acquired from ouside sources.
Congenital
hair loss is related to the patient’s family back
ground. The doctor finds clues frim other members of
the family having similar hair loss diseases and the
genetic relationship.
For acquired
hair loss diseases the questions are directed to health
and lifestyle.
Diagnostic
tools to identify hair loss
Diagnostic
tools that diagnose hair loss diseases include the hair
pull test. This pull test is done by grasping a lock
of hair between the thumb and forefinger that contains
around 50 hairs. he fingers grasping the hair are dragged
along the length of the hair (without plucking). This
methodology gives a rough idea about the quantity of
hair shed.
Hair pull
test for diagnosing hair loss diseases
The number
of hairs that are pulled out gives an indication of
how many hair follicles are in a telogen resting state.
Telogen hairs are easier to pull out than anagen growing
hair. So in the pull test, telogen hairs will come out
but the anagen hairs remain rooted in the scalp.
Normally,
around 5 to 15 hairs can be pulled out from a normal
scalp. More than 15 hairs suggests an increased number
of hair follicles are in telogen. Telogen hairs are
easier to pull out than anagen growing hair. When pulled,
telogen hairs will come out but the anagen hairs remain
rooted in the scalp.
The
hair pull test can be inaccurate as the number of hairs
removed varies as it also depends on how long it was
since the person washed their hair or how frequently
they brush their hair. These activities pull out telogen
hairs.
Hair pluck
test to diagnose hair loss diseases
Also known
as trichogram, the objective of the hair pluck test
is to pull a number of hairs from the scalp to examine
their roots. The procedure involves using rubber tipped
tweezers that grasp about 50 hairs at a time. The proceduret
can be painful but brief. These hairs are are cut off
from the upper part to remove the excess length leaving
1 cm in length with the root intact.
A dye of
4-dimethylaminocinnamaldehyde dye is applied to stain
the hair root that is floated on the slide. Only the
hair roots that have intact internal root sheaths which
are present only in anagen hairs will stain. Telogen
hairs will not be stained as it is devoid of intact
internal root sheath. The doctoe can then count how
many telogen and anagen hairs are present. Roots of
the hair fiber that might suggest a hair shaft defect
are also revealed
Identify the diseases through laboratory
tests
Laboratory
tests may be recommended for hair loss unexplained above.
They may include applying potassium hydroxide on scalp
scrapings to test for fungal elements. This test is
commonly recommended for patients with localized hair
loss. Alopecia Areata and scalp ringworm are localized
hair loss.
The presence
of ringworm, a fungal disease is confirmed with a positive
result. Other tests may involve culturing the scrapings
to determine the kind of bacteria or fungi present.
Blood samples may be tested to look for inflammation,
minerals, or viral infections.
Skin biopsy
to diagnose hair loss
Hair loss
diseases like cicatrical alopecia can be confirmed through
skin biopsies. It uncovers inflammation from the intensity
that the hair follicles are destroyed.
In a small
skin biopsy, 2-4mm in diameter is taken from the scalp
and processed for examination under a microscope.
Summary
Questioning
and laboratory tests form most of the diagnostic tests.
They are straight forward and do not take long. Then
the treatment of the hair loss disease is selected.
More
on causes of hair loss is dicussed in the relevant web
page.
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