Thyroid disorders, tests, how to treat
What is hyperthyroidism? --- causes, symptoms, effects
What is hyperthyroidism?
Hyperthyroidism occurs when
overactive thyroid tissue produces TOO MUCH thyroid hormone
(T3 and T4)
Hyperthyroidism can be a cause of /
lead to:
Thyrotoxicosis.
An excessive presence of thyroid
hormones.
Diffuse toxic goiter / Graves disease
Thyroid cancer
What causes hyperthyroidism?
Hyperthyroidism occurs as a consequence of
any of the following conditions:
Iodine
deficiency . Hydrogen peroxide (H2 O2 )
and the thyroid peroxidase enzyme (TPO) help oxidize
iodide to iodine
needed to make thyroid hormones; A deficiency of
iodine results in an excess amount of unused
H2 O2 , which is able
to damage TPO; the body's response to damaged TPO is to produce
antibodies against TPO (anti-TPO antibodies), leading
to so called autoimmune diseases E.g. Hashimoto's thyroiditis and
Graves Diseas e (70-90% of
Hyperthroidism cases) - Provision of
iodine stops the injury to TPO, which resolves
the condition.
Thyroid cells damaged by inflammation,
which release too much thyroid hormone into the blood stream.
Hypothyroidism usually follows because the damaged thyroid
is not producing enough thyroid hormone and the stored hormones are eventually depleted.
Inflammation can be induced by several factors, including auto-antibodies
(E.g. in Graves disease ), microbial infection, radiation
damage, toxins, food allergies (i.e., gluten intolerance), and nutritional
imbalances.
TSH
Receptor Antibodies (TRAbs). Auto-antibodies
that bind to TSH receptors on thyroid follicular cells and continuously
stimulate the thyroid to secrete T4 and T3, which quantities become excessive.
TRAbs are detected in >90% of
Graves Disease patients.
Examples of Hyperthyroid
hormone levels
Hormone
Example Hyperthyroid level
Normal level range
T4
50.3 pmo1/L
8.0 - 23.0 pmo1/L
T3
6.5 nmo1/L
0.9 - 2.8 nmo1/L
TSH
< 0.10 mU/L
0.40 - 5.00 mU/L
Symptoms / Effects of
HYPERthyroidism
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
Hyperthyroid
hormonal effects
Excess TH stimulates release of adrenocorticotropic hormone (ACTH),
the "stress"hormone. This causes adrenals to kick
into high gear with "fight-or-flight" reactions, such as increasing heart-rate,
breathing, blood pressure and body temperature, hormonally controlled
by:
EPINEPHRINE.
Increases heart-rate, opens airway to bring in more oxygen with each breath,
constricts blood vessels to non-vital organs to provide blood to vital organs;
NOREPINEPHRINE.
Constricts major blood vessels and increases blood pressure;
CORTISOL.
Increases INSULIN sensitivity,
allowing cells to "Burn" more
glucose for energy;
Your body can sustain this heightened state for a
limited time before experiencing cell and tissue damage
Health problems associated with excess thyroid hormone
Atrial fibrillation and tachycardia
Increased cell metabolism. This signals
the pancreas to produce more INSULIN to
burn more glucose,
and decreases glucose conversion for fat
storage .
Alters vitamin metabolism
Draws calcium from bones. Partly because
of altered vitamin metabolism and also to meet calcium needs of "speeding" cardiac
system.
Thyroid damage
Grave's
Disease (70-90% of hyperthyroidism) .
Common thyroid-specific autoimmune disease, unique in being associated with
target organ hyperfunction rather than organ damage; affects~ 4 in 10,000 people
/ year;
Grave's Disease
Thyroiditis.
E.g. Due to:
Inflammation in Autoimmune Hashimoto's Thyroiditis or inflammation
caused by toxic substances/radiation exposure. May develop
an overactive thyroid (rather than
the usual hypothyroidism) for a short
period, due to release of thyroid hormone from damaged thyroid cells .
This is followed by a usually short-lived period of time when the thyroid functions
properly, and as scarring sets in, hypothyroidism
results .
Postpartum thyroiditis (first
phase)
Drugs
/ iodine. E.g. Amiodarone (CORDARONE), interferon-alpha,
and lithium (LITHOBID); excess iodine from
supplements, certain expectorants, or iodine -containing
contrast agents for x-ray studies may cause hyperthyroidism.
Thyroid cancer
Toxic thyroid nodules
Overstimulation due to overactive pituitary (rare
cause);