Hyper/Hypothyroidism Flashcards
Causes of Hypo?
Hashimoto’s thyroiditis, an autoimmune disorder
Genetics
Low-iodine diet
Radiation exposure from cancer treatment
Certain medications used to treat cancer, heart problems and psychiatric conditions
Surgical removal of the thyroid
Symptoms of hypo?
Unexplained weight gain or trouble losing weight Fatigue Depression Hair loss and dry hair Muscle cramps Dry skin Goiter (swelling of thyroid gland) Brittle nails Amenorrhoea Reduced libido Slow heart rate Irregular period Sensitivity to cold Constipation Carpal tunnel syndrome
Causes of Hyper?
Graves disease, a common autoimmune condition that stimulates the thyroid hormones T4 and T3
Swollen thyroid
Thyroid nodules
Symptoms of hyper?
Unexplained weight loss Feeling wired or anxious Racing heartbeat Shakiness Sweating spells Feeling hot, frequently Itchy red skin Gynaecomastia (in men) Goiter More frequent bowel movements than usual Fine hair and hair loss
Sings if Hyper?
Goitre Sinus tachycardia/arrhythmias Myxoedema - deposition of mucopolysaccharides in the skin leading to swelling. Hair loss Palmar erythema Tremor Thyroid bruit (Graves’)
Signs of Hypo?
Hair loss - characteristically the outer third of the eyebrows
Dry skin
Goitre
Bradycardia
Myxoedema - deposition of mucopolysaccharides in the skin leading to swelling
Delayed relaxation phase of deep tendon reflexes
Thyroid hormone affects the rate of
one replacement. Too much thyroid hormone (i.e. thyroxine) in your body speeds the rate at which bone is lost. If this happens too fast the osteoblasts may not be able to replace the bone loss quickly enough.
If the thyroxine level in your body stays too high for a long period or the thyroid-stimulating hormone (TSH) level in your body stays too low for a long period then there is a higher risk of developing osteoporosis
Thyroid hormone signaling is required for
skeletal muscle development, contractile function and muscle regeneration.
As skeletal muscle comprises 30–40% of body mass, the altered
the altered basal metabolic rate in patients with thyroid hormone excess or deficiency is largely due to changes in skeletal muscle energy turnover.
In the absence of DIO2, the muscle-specific thyroid hormone-dependent gene expression programme
fails to be induced in the stem cell-like satellite cells of skeletal muscle, resulting in impaired muscle regeneration.
Expression of the Type 2 iodothyronine deiodinase (DIO2), which converts the prohormone
T4 to the active thyroid hormone isoform T3, is increased in developing or injured muscles.
Hyperthyroidism is an important cause of
secondary osteoporosis
Western data suggest that these patients have hypercalcemia, hyperphosphatemia, raised alkaline phosphatase and reduced BMD. However, the available data from India suggest that due to concomitant vitamin D deficiency, these patients have normal calcium levels and increased bone loss.
Hypothyroidism effect on bones?
It seems that there is increase in bone density in adult subjects with hypothyroidism, but the bone quality is poor which is responsible for the possible increase in fracture in these patients.
Some studies have related hypothyroidism to muscle dysfunction. The problem seems to lie in
the lower activity of the enzymes involved in the aerobic and anaerobic glucose mechanism.
Reduced mitochondrial activity also occurs, with abnormal muscle energy metabolism.
thyroid hormone action on skeletal muscles affects mainly
type-I muscle fibers, which promote slow contractions and are most prevalent in the postural muscles recruited during prolonged effort.
