Download Thyroid gland & mechanism,Definition,Classification,Symptoms,Risk

This lecture was conducted during the
Nephrology Unit Grand Ground by Medical
Student rotated under Nephrology Division under
the supervision and administration of Prof. Jamal
Al Wakeel, Head of Nephrology Unit, Department
of Medicine and Dr. Abdulkareem Al Suwaida.
Nephrology Division is not responsible for the
content of the presentation for it is intended for
learning and /or education purpose only.
Outlines:
Thyroid gland & mechanism
Goiter:
Definition
Classification
Causes
Symptoms
Risk factor
Tests and diagnosis
Treatments
Lifestyle
The thyroid is a small, butterflyshaped gland inside the neck, just
below the Adam’s apple. The
thyroid gland produces hormones
which control the body’s
metabolism and regulate the rate
at which the body carries out its
functions
Definition:
A goiter is an abnormal enlargement
of the thyroid gland and can occur for
a number of different reasons.
.
Mortality/Morbidity:
Most goiters are benign, causing
only cosmetic disfigurement.
Morbidity or mortality may result
from compression of surrounding
structures, thyroid cancer,
hyperthyroidism, or hypothyroidism.
Sex and age:
The female-to-male ratio is 4:1
In the Wickham study, 26% of
women had a goiter, compared to
7% of men.
Thyroid nodules are less frequent in
men than in women, but when
found, they are more likely to be
malignant.
Classification:
Toxic goiter: A goiter that is
associated with hyperthyroidism is
described as a toxic goiter.
Examples of toxic goiters include
diffuse toxic goiter (Graves
disease), toxic multinodular goiter,
and toxic adenoma
Nontoxic goiter: A goiter without
hyperthyroidism orhypothyroidism
is described as a nontoxic goiter.
It may be diffuse or multinodular
Examples of nontoxic goiters
including goiter identified in early
Graves disease, congenital goiter,
and physiologic goiter that occurs
during puberty
Other type of classification:
I - palpation struma - in normal
posture of head it cannot be seen.
Only found when palpating.
II - struma is palpative and can be
easily seen.
III - struma is very big and is
retrosternal. Pressure and
compression marks.
Causes:
Worldwide, the most common cause
for goiter is iodine deficiency. In
countries that use iodized salt,
Hashimoto's thyroiditis becomes
the most common cause.
- Excess iodine or lithium ingestion, which
decrease release of thyroid hormone
-Goitrogens(cassava, lima beans, maize,
bamboo shoots, and sweet potatoes)
-Inborn errors of metabolism
causing defects in biosynthesis of
thyroid hormones
- Exposure to radiation
-Thyroid hormone resistance
Side-effects of pharmacological therapy
such as:
Amiodarone :
inhibits peripheral conversion of thyroxine to
triiodothyronine; also interferes with
thyroid hormone action.
Phenobarbitone, phenytoin, carbamazepine,
Rifampcin:
induce metabolic degradation of T3 and T4.
Graves' disease
Thyroiditis
Thyroid cancer
Graves' disease
one’s immune system produces a
protein, called thyroid stimulating
immunoglobulin (TSI). As with
TSH, TSI stimulates the thyroid
gland to enlarge producing a
goiter. However, TSI also
stimulates the thyroid to make too
much thyroid hormone (causes
hyperthyroidism).
It can also affect the eyes, causing
bulging eyes (exophthalmos). It
affects other systems of the body,
including the skin, heart, circulation
and nervous system.
Thyroiditis:
it is the inflammation of the thyroid
gland.This disease is often considered a
malfunction of the immune system.
Antibodies that attack the thyroid are
what causes most types of thyroiditis.
It can also be caused by an infection,
like a virus or bacteria.
Hashimoto's thyroiditis:
This is a autoimmune condition in
which there is destruction of the
thyroid gland by one’s own immune
system.
As the gland becomes more
damaged, it is less able to make
adequate supplies of thyroid
hormone.
The pituitary gland senses a low
thyroid hormone level and
secretes more TSH to stimulate
the thyroid. This stimulation
causes the thyroid to grow, which
may produce a goiter .
Thyroid neoplasm or thyroid
cancer
usually
4 kinds of malignant tumors of the
thyroid gland:
papillary, follicular, medullary or
anaplastic
Symptoms:
In general:
-Swelling or disfigurement of the
neck
-Afeeling of tightness in the throat
-Coughing
-Difficulty breathing
-Difficulty swallowing
Hyperthyroidism:
Weight loss, heat intolerance,
trembling hands, palpitations,
insomnia, anxiety,
increased bowel movement
frequency.
Hypothyroidism:
Weight gain, cold intolerance,
constipation, very dry skin,
depressed mood, muscle cramping .
Symptoms of Possible
Cancer Spread:
Bone pain in one spot without relief
Weakness or numbness of an arm or leg
that persists .
Examination of the goiter is best
performed with the patient
upright, sitting or standing.
Inspection from the side may
better outline the thyroid profile,
as shown below. Asking the patient
to take a sip of water facilitates
inspection. The thyroid should
move upon swallowing .
Palpation of the goiter is performed
either facing the patient or from behind
the patient, with the neck relaxed and
not hyperextended.
Each lobe is palpated for size,
consistency, nodules, and tenderness.
Cervical lymph nodes should be palpated.
Palpation of the goiter rules
out a pseudogoiter, which is
aprominent thyroid seen in
individuals who are thin.
The pyramidal lobe often is enlarged
in Graves disease.
A firm rubbery thyroid gland suggests
Hashimoto thyroiditis.
Multiple nodules may suggest a
multinodular goiter or Hashimoto
thyroiditis.
A solitary hard nodule suggests
malignancy, whereas a solitary firm
nodule may be a thyroid cyst.
Diffuse thyroid tenderness suggests
subacute thyroiditis, and local
thyroid tenderness suggests intranodal
hemorrhage or necrosis.
Cervical lymph nodes are palpated
for signs of metastatic thyroid cancer
Auscultation of a soft bruit
over the inferior thyroidal artery
may be appreciated in a toxic
goiter. Palpation of a toxic goiter
may reveal a thril.
Risk factor:
A lack of dietary iodine.
sex. Because women are more prone
to thyroid disorders than men
age. Being age 50 or older
Medical history. A personal or
family history of autoimmune
disease
Pregnancy and menopause.
Certain medications.
immunosuppressants,
the heart drug amiodarone
and the psychiatric drug lithium
Radiation exposure.
Tests and diagnosis
Hormone test:
If the thyroid is overactive,the
level of thyroid hormone in the
blood will be high and the level of
thyroid stimulating hormone (TSH)
will be low
If the thyroid is underactive the
level of thyroid hormone will be
low while the level of TSH will be
high.
Antibody test:
auto-immune antibodies.
Ultrasonography:
To show the size of the thyroid
gland and the presence of any
nodules.
Fine needle aspiration biopsy
Thyroid scan:
This scan will help evaluate the
structure and function of the
thyroid and involves the
administration of radioactive
substance.
Treatment:
Small benign euthyroid goiters do
not require treatment.just
observe.
iodine supplementation by mouth
If hypothyroidism
thyroid hormone replacement with
levothyroxine(Levothroid,Synthroid)
aspirin or a corticosteroid
medication to treat the
inflammation.
Hyperthyroidism:
anti-thyroid drugs such as
methimazole (Tapazole) or
propylthiouracil (PTU).
For advanced hyperthyroidism,
radioactive iodine treatment (RAI)
.
Surgery
Large goiters with compression
Malignancy
When conventional drug therapy for
overactive thyroid is not
successful
Lifestyle:
Get enough iodine(Sea vegetables,
Yogurt, cow's milk, eggs, and
strawberries )
The recommended minimum daily intake
of iodide is 150 mcg for adults, 220
mcg for pregnant women, and 290 mcg
for lactating women.
avoid excessive consumption.
Avoid Goitrogens (Foods that
contain cyanoglucosides include
cassava, lima beans, maize, bamboo
shoots, and sweet potatoes.)
Done by
Ibtisam Al-Qahtani
425200245