Metabolic Disorders of the Thyroid and Adrenal Glands Flashcards
metabolic syndrome
a cluster of metabolic risk factors; excessive abdominal fat, high blood pressure, high triglyceride and/or cholesterol levels, high blood sugar. These risk factors can result in serious disease, such as heart disease and type 2 diabetes
inborn errors of metabolism- rare disorders (hundreds are known, such as)
–Carbohydrate metabolism (ex: glycogen storage disease)
–Amino acid metabolism (ex: phenylketonuria)
–Organic acid metabolism (ex: alcaptonuria)
–Urea Cycle
–Fatty acid metabolism
–Porphyrin metabolism
–Purine Pyrimidine metabolism
–Steroid metabolism
–Mitochondrial function
–Peroxisomal function
–Lysosomal storage diseases
–Metal metabolism
–Congenital disorders of glycosylation
–Congenital disorders of creatine metabolism
diseases of the thyroid gland (3)
–Goiter (abnormally large thyroid)
–Graves disease (hyperthyroidism)
–Hashimoto’s disease (hypothyroidism)
diseases of the adrenal gland (2)
–Addison’s disease (aldosterone and cortisol insufficiency)
–Cushing’s syndrome (cortisol excess)
what is the largest endocrine gland in the body? weight?
thyroid
15-20 gm
what does the thyroid produce
thyroid hormones and calcitonin
location of the thyroid
it sits between anterior to the trachea
physical description of the thyroid
consists of two lobes and a central isthmus, which gives it a bow tie like shape
the thyroid is the only tissue in the body capable of
absorbing iodine
Iodine deficiency can lead to a variety of health and developmental consequences known as
iodine deficiency disorders (IDDs)
what is the most widely used strategy to control and eliminate IDDs?
universal salt iodization
universal salt iodization aims for consumption of adequately iodized salt in more than
90 per cent of households. However, this goal is a long way from being met
Iodine deficiency is especially damaging during
the early stages of pregnancy and in early childhood
In their most severe forms, IDDs can lead to (4)
cretinism, stillbirth and miscarriage; even mild deficiency can cause a significant loss of learning ability
Adequately iodized salt can protect children from
brain damage, but only three quarters of the world’s households are using it. In 2013, more than 35 million newborns were unprotected from the lifelong consequences of brain damage associated with iodine deficiency
one of the most common glandular disorders of the endocrine system
thyroid dysfunction
how much of the world lives in areas of iodine deficiency?
1/3
incidence of thyroid disorders
higher in females (9%) vs males (2%)
abnormal thyroid prevalence
about 15% of the population
most common findings of abnormal thyroid
thyroid nodules
what is the major form of thyroid hormone found in the blood?
thyroxine, T4
T4 is cleared into
3, 5, 3’ triiodothyronine (T3)
3, 3’, 5’ triiodothyronine (reverse T3)
metabolically active form of T3
3, 5, 3’ triiodothyronine (T3)
metabolically inactive form of T3
3, 3’, 5’ triiodothyronine (reverse T3)
T4 is the major form found in blood, because
it has a longer half-life than T3
T4 is converted to active T3 in target cells by the
deiodinase enzyme (or iodide peroxidase) Iodothyronine deiodinase.
three isoforms (Type 1, 2 and 3) of Iodothyronine deiodinase and these enzymes contains a
selenium metal ion (in the form of selenocystiene)
Selenium deficiency can lead to
decreased T3 levels
Synthesis of thyroid hormones involves the protein
thyroglobulin
TRH
thyrotropin releasing hormone
TSH
thyroid stimulating hormone
how is T4/T3 production regulated?
negative feedback regulation look at the levels of the pituitary and hypothalamus
production of T4/T3
hypothalamus released TRH which stimulates the pituitary gland to release TSH which stimulates the thyroid gland to produce and secrete T3 and T4 which is converted to T3 in peripheral tissues
Hyperthyroidism often
mimics other diseases
hyperthyroidism can greatly accelerate your body’s
metabolism
common symptoms of hyperthyroidism include (5)
–Heart problems: arrhythmia or atrial fibrillation
–Osteoporosis: too much thyroxine interferes with process of bone formation and calcium handling
–Eye problems: Graves ophthalmopathy
–Red swollen skin: increased sensitivity to heat
–Thyrotoxic crisis: sudden intensification of symptoms
–Abnormal thermal regulation: night “sweats”
–Brittle hair
Graves Disease
Autoimmune disorder resulting in overproduction of thyroid hormones
~30% of patients develop
Graves’ ophthalmopathy
The autoimmune reaction is due to
an antibody that binds to the thyrotropin receptor, which stimulates the thyroid to overproduce thyroid hormones
In rare circumstances patients can develop a
thyroid storm or thyrotoxic crisis. This is a life-threatening condition and must be treated immediately
who is most likely to get hypothyroidism?
More common in women over age 60, but anyone, including infants can develop hypothyroidism
common symptoms of hypothyroidism (8)
–Fatigue–Sensitivity to cold –Constipation –Dry skin –Weight gain –Puffy face –Hoarseness –Muscle weakness, aches, tenderness and stiffness –Thinning hair
Hashimoto Syndrome
Autoimmune disease (T-cell mediated) in which your immune system attacks the thyroid
Hashimoto Syndrome results in
hypothyroidism
Hashimoto Syndrome affects about
5 in 100 people in the US
who is most likely to develop Hashimoto Syndrome
Women are ~8X more likely to develop than men
Several diseases are risk factors, such as (6)
Addison’s disease, celiac disease, pernicious anemia, Sjogren’s syndrome, type 1 diabetes, vitiligo
patients with Hashimoto Syndrome often develop a — as the disease progresses
goiter
dental complications of radioiodine therapy (2)
- Xerostomia or dry mouth
* Increased risk of caries due to changes in oral microbiome
radioiodine therapy is a treatment of
thyroid cancer because the thyroid is the only organ that produces iodine
The danger of low dietary iodine is further compounded by your body’s decreased ability to utilize it, the result of contamination by a ubiquitous environmental toxin called
perchlorate
what is perchlorate used for?
Originally developed for explosives and rocket fuel, perchlorate now pervades ground water and food supplies throughout the US. It’s even used as a flavor-enhancer in certain foods.
how does perchlorate act?
blocks the thyroid gland’s ability to absorb and utilize dietary iodine, an effect that is of concern when iodine intake drops off.
5 steps to do an iodine deficiency test on yourself
- Use tincture of iodine (the orange variety) to paint a 2-3-inch square patch on the inside of your forearm, the inside of a thigh, or your abdomen.
- Inspect the painted area in less than 8 hours. If all the color is gone, then you definitely have an iodine deficiency.
- If after 24 h, all the color is gone, you also likely need iodine.
- If the color simply remains on your arm and begins to slowly fade in color after 24 h, you have reached iodine sufficiency.
- You can repeat the test in a month or so after supplementing with iodine to see how you’re doing.
where are adrenal glands located?
on top of the kidneys
two parts of the adrenal glands?
cortex and medulla
what does the cortex produce? (3)
mineralocorticoids
glucocorticoids
adrenal androgens
what does the medulla produce?
catecholamines
main mineralocorticoid
aldosterone
main glucocorticoid
cortisol
main adrenal androgens (2)
DHEA
testosterone
main catecholamines (2)
adrenaline (epinephrine)
noradrenaline (norepinephrine)
examples of diseases of adrenal gland dysfunction in humans (4)
Cushing disease
addisons disease
hyperaldosteronism
pheochromocytoma
Cushing disease
adrenal overproduction of cortisol
Addisons diease
adrenal underproduction of cortisol
hyperaldosteronism
increase aldosterone, which control blood pressure and body stat and potassium levels
phenochromocytoma
high levels of adrenaline
cushings syndrome oral signs (3)
fatty tissue deposition (moon face)
osteoporosis (pathological fractures of the mandible, maxilla, or alveolar bone
delayed healing of fractures and also soft tissue injuries
Addisons disease (oral signs) (2)
bronzing hyperpigmentation of the skin
oral mucosal melanosis (buccal muscosa, tongue)
Addisons disease causes an increased production of melanin, results in
melanotic macules in the oral mucosa
the thyroid gland produces (2)
T3 and T4
what are T3 and T4 produced from?
iodination of thyroglobulin
thyroglobulin is degraded to release (2)
T3 and T4
major circulating form
T4
