Thyroid disorders, tests, how to treat
Thyroiditis - Inflammation of the thyroid gland
Thyroiditis - Inflammation
of the thyroid gland
Thyoiditis types either autoimmune or non-autoimmune depending
on the cause of inflammation
Autoimmune Thyroiditis:
• Immune system is attacking the thyroid. Includes
Hashimoto's disease , Postpartum thyroiditis,
SIlent/Painless thyroiditis
Non-autoimmune thyroiditis:
• Microbial infection.
Includes Acute infectious thyroiditis, Sub-Acute thyroiditis
• Toxic substances.
Includes Drug-induced thyroiditis, thyroiditis from radiation exposure
Types of thyroiditis
What Causes Thyroiditis?
Thyroiditis is the result of an attack on the thyroid
gland. An attack causes inflammation, damage
and possible death of thyroid gland cells (thyrocytes).
- Most
types of thyroiditis are 3-5 times more prevalent in women than in men
- Average
age of onset is between 30 and 50 years of age
- Tends to
be geographical/seasonal. Most common in summer and
fall;
- The
various types of thyroiditis usually have both
hypothyroid
and
hyperthyroid
phases
Symptoms of Thyroiditis
Thyroiditis can cause slow, long-term damage to
thyrocytes that cause blood thyroid hormone levels to fall ▼▼▼.
If this happens, symptoms are similar to hypothyroidism
(under-active thyroid) :
May include:
• Feeling constantly fatigued
• Aching muscles / Vague aches and pains
• Cold hands and feet
• Weight gain without eating more
• Coarse, dry, thinning hair
• PMS /Heavy menstrual periods / menstrual cramps
• Dry skin
• Forgetfulness
• Slow heartbeat
• Loss of libido
• Mental sluggishness/"Fuzzy headed"
• Constipation
• Depression
• Pain in thyroid gland (at front of neck)
• Low basal temperature
• Infertility /anovulatory cycles / repeated miscarriage
• Slowed knee-jerk reflexes
Thyroiditis can cause rapid thyroid cell damage/destruction
that causes thyroid hormone in the gland to leak out and so increase the blood thyroid
hormone levels ▲▲▲.
This causes symptoms similar to hyperthyroidism
(over-active thyroid). The excess presence of thyroid hormones is referred
to as thyrotoxicosis.
Typical Symptoms Include:
• Weight loss -despite increased appetite
• Nervousness, Anxiety, irritability
• Heat intolerance
• Tremors in hands/fingers
• Muscle weakness/aches
• Fatigue
• Excessive production/excretion of urine (Polyuria) /
Excessive thirst
• Hyperactivity
• Apathy
• Hypoglycemia
• Non-pitting edema over the shin (Pretibial myxedema)
• Sweating
Can also include:
• Palpitations/ increased heart rate / arrhythmia
• Memory loss
• Diarrhea
• Insomnia
• Loss of libido
• Pain in thyroid gland (at front of neck)
• Shortness of breath (dyspnea)
• Light/absent menses
• Nausea/Vomiting
Types of thyroiditis
Autoimmune Thyroiditis (Immune system antibodies attack the thyroid)
Iodine -deficient patients
shown to have higher rate of anti-thyroid antibodies
A malfunctioning immune system causes some people to
make anti-thyroid antibodies.
Acting as if the thyroid gland is foreign tissue, the anti-thyroid
antibodies involved with autoimmune thyroiditis are:
• Anti-thyroid peroxidase (TPO Ab).
These antibodies attack the thyroperoxidase enzyme (TPO), responsible
for thyroid hormone production.
• Anti-thyroglobulin (Tg Ab).
These antibodies block a protein made by the thyroid, necessary for
making thyroid hormones.
• TSH Receptor Antibody (TRAb).
These antibodies stimulate thyroid hormone production by binding
to Thyroid Stimulating Hormone (TSH) receptors.
Anti-thyroid
Antibodies
Hashimoto's disease
(also called
lymphocytic or autoimmune thyroiditis)
Most common
cause of hypothyroidism
in N. America. First described by Dr. Hakuru Hashimoto in Japan, 1912.
Autoimmune
disease. The thyroid gland is gradually destroyed by a
variety of cell and antibody- mediated immune processes;
Both TPO Ab and Tg Ab
are elevated in most Hashimoto's cases. The inflamed gland causes it to swell.
Occurs
more often in women than in men (between 10:1 and 20:1).
Most prevalent between 45 and 65 years of age; an average of 1 - 1.5
in a 1000 people have this disease;
Often results
in hypothyroidism
with bouts of hyperthyroidism .
Postpartum
thyroiditis
Diffuse
goiter usually present. Typically 1.5 - 3 times normal
gland size
Affects ~5% of women within a year of giving birth and is an exacerbation
of an underlying autoimmune thyroiditis. Aggravated by the immunological
rebound that follows the partial immuno-suppression of pregnancy.In
essence, the immunological rebound that follows the end of pregnancy precipitates
the clinical expression of Hashimoto's disease, which before pregnancy was clinically
silent.
Muller AF, Drexhage HA,
Berghout A. Postpartum thyroiditis and autoimmune thyroiditis in women
of childbearing age: recent insights and consequences for antenatal and postnatal
care. Endocr Rev. 2001 Oct;22(5):605-30.
PubMed
First Phase.
Hyperthyroidism occurs 1-4 months
after delivery, lasts only 2-4 months. Of those with postpartum thyroiditis in the
hyperthyroid phase, 25% are found to have
TRAb antibodies and ~80% have a positive test result
for TPO Ab . Associated symptoms include anxiety,
insomnia, palpitations (fast heart rate), fatigue, weight loss, and irritability.
This phase of postpartum thyroiditis can be confused with Grave's disease. When
present, either exophthalmos (bulging eyes) or a thyroid bruit (audible sound of
increased blood flow over hyperactive gland) confirms Graves'disease. After the
hyperthyroid phase, the thyroid then returns to normal or progresses to:
Second
phase. Hypothyroidism
3-9 months after child-birth; typical symptoms include fatigue, weight gain, constipation,
dry skin, depression and poor exercise tolerance. Most cases resolve after about
12-18 months, but 1 in 5 of these women will develop permanent
hypothyroidism.
Silent / painless thyroiditis
(also called
subacute lymphocytic thyroiditis)
Tends to have a phase of hyperthyroidism
/thyrotoxicosis followed by a return to normal, and then a phase of
hypothyroidism , followed again by a return to normal.
The time span of each phase can vary, each typically lasting 2-3 months. During
the hyperthyroid phase,
iodine uptake is suppressed, while during the hypothyroid phase, uptake is
increased. This is different to the elevated iodine
uptake found in those with Grave's disease.
Non-autoimmune thyroiditis
Infectious Microbes
(E.g. bacteria, virus)
Acute infectious thyroiditis.
E.g. mainly bacterial infection, but any microbial
infection , which works in the same way as antibodies to cause inflammation;
uncommon form of thyroiditis; occasionally painful; mild
hypothyroiditis
Subacute thyroiditis (also called de Quervain's thyroiditis). Presumed caused
by a virus (often follows an upper respiratory infection); can be a cause of
hypothyroiditis and painful
hyperthyroiditis /thyrotoxicosis ; different to
post-partum and silent thyroiditis in that this type is associated with pain (usually
in hyperthyroid phase);Also, may trigger autoreactive
B cells to produce TSH (thyrotropin) receptor antibodies
(TRAb), resulting in TRAb - associated thyroid
dysfunction in some patients.
Iitaka, M, Momotani, N, Hisaoka, T, Noh, JY, Ishikawa,
N, Ishii, J, Katayama, S Ito, K 1998 TSH receptor antibody-associated thyroid dysfunction
following subacute thyroiditis Clin Endocrinol (Oxf) 48
:445-453. PubMed
Toxic Substances
Drug-induced thyroiditis.
Drugs such as lithium, amiodarone (cordarone - high
iodine content, used for arrhythmia), interferon and cytokines have a tendency to
damage thyroid cells. Either thyrotoxicosis (excess thyroid hormone) or
hypothyroidism ;
Radiation exposure follows treatment with radioactive
iodine for hyperthyroidism,
or external beam radiation therapy for certain cancers.
This frequently leads to hypothyroidism,
and occasionally thyrotoxicosis (excess presence
of thyroid hormone).