endocrine Flashcards
what is hyperthyroidism?
caused by the effects of too much thyroid hormone; excess sysnthesis and sectretion of thyroid hormone by the thyroid gland
what is the epidemiology of hyperthyroidism?
Gender -Women>men (Graves’, female-to-male: 5-10 to 1.) Ag Age -Graves: 20-40yrs -Toxic multinodular goiter: >50yrs Race -Graves: Caucasians/ Asians/Hispanics
what are some constitutional signs/symptoms of hyperthyroidism?
Sweating, warm/moist skin, muscle weakness, weight loss, increased appetite
what are some cardiac signs/symptoms of hyperthyroidism?
Increased HR, high-output CHF, cardiomegaly, pulm/peripheral oedema, MVP, Afib, heart block, dysrhythmias
- Resistant to digitalis/ cardiac glycosides
- ‘apathetic’ (i.e. blunted signs/sx) hyperthyroidism in patients age>60, cardiac manifestations predominate, e.g. AFib.
what are some pulmonary signs/symptoms of hyperthyroidism?
Increased respiratory rate, increased minute ventilation
what are some neurological signs/symptoms of hyperthyroidism?
Anxiety, confusion, tremor, seizures
what are some GIT signs/symptoms of hyperthyroidism?
Secretory diarrhea, increased alkalising phosphate
what are some blood related signs/ symptoms of hyperthyroidism?
Decreased WBC, decreased haemoglobin, decreased platelets
what are some renal signs/symptoms of hyperthyroidism?
Decreased potassium excretion, increased sodium excretion
what are some ocular signs/symptoms of hyperthyroidism?
Exophthalmus
what are some dermatome signs/ symptoms of hyperthyroidism?
Vitiligo, hyperpigmentation (skin and hair lose integrity)
what are some psychological signs/ symptoms of hyperthyroidism?
Emotional instability, insomnia
What is thyroid storm?
Acute, severe, exacerbation of thyrotoxicosis due to acute increased serum T3/T4
-Dumps all T3/T4 out of your system
What can cause thyroid storm?
DKA, infection, acute I- tx withdrawal, trauma, thyroid gland manipulation, radioactive I-, surgery, ether anesthesia
What are some signs of thyroid storm
Increased T Increased HR CHF Confusion Increased Gllc Shock Death
what are some decreased energy production symptoms of hypothyroidism?
weakness, fatigue, cold intolerance, lassitude, weight gain, decreased oxygen consumption, constipation, bradycardia, hypotension
what are some decreased protein synthesis symptoms of hypothyroidism?
anaemia, dry sparse hair, dry scaly skin
what are some decreased CNS activity symptoms of hypothyroidism?
memory loss
drowsiness
apathy
what are some decreased liver function symptoms of hypothyroidism?
elevated plasma lipids, elevated plasma cholesterol, atherosclerosis, decreased vitamin A synthesis
what are some mucoprotein synthesis symptoms of hypothyroidism?
water retention
non pitting oedema (myxedema)
husky voice (oedema of vocal cords)
what is the epidemiology of thyroid nodules
It is estimated that the prevalence of thyroid nodules in the general population is 4 -7%
Benign adenomas or cysts account for approximately 90% of detected thyroid nodules
In the U.S., ~10,000 to 17,000 new cases of primary thyroid cancer are diagnosed each year
1,000 - 2,000 people die each year from primary thyroid carcinomas
who is of low suspicion of thyroid nodules?
Family history of autoimmune disease (eg, Hashimoto’s thyroiditis)
Family history of benign thyroid nodule or goitre
Presence of thyroid hormonal dysfunction
Pain or tenderness associated with nodule
Soft, smooth, and mobile nodule
who is of high suspicion of malignancy in thyroid nodules
family history of medullary thyroid carcinoma or multiple endocrine neoplasia
rapid tumour growth
firm/hard nodule
fixation of the nodule to adjacent structures
paralysis of vocal cords
distant metastases
what are some risk factors for thyroid carcinoma?
- Age (<20 or >60)
- Male sex
Prior radiation
Family history
Family history of medullary carcinoma, pheochromocytoma, hyperparathyroidism (MEN syndrome)
Respiratory distress, voice changes, hoarseness, cough, dysphagia
Rapid growth of lesion
Ipsilateral lymph node enlargement
Long-standing goitre
what are some risk factors for cold nodules?
Thyroiditis Fibrosis Cyst Non-functioning Adenoma Multinodular Goitre Malignancy
what are some risk factors for hot nodules?
- Functioning adenoma
Thyroiditis
Multinodular goitre
what is the use of ultrasound in thyroid imaging
Helpful for determining the nature of the nodule, whether cystic, solid, or mixed
Knowing the exact location of the nodule and the size can be helpful when planning FNAB
Used to exclude the presence of other nodules, which indicates a multinodular disease process
Facilitate fine needle aspiration biopsy of a nodule
Assess the comparative size of nodules, lymph nodes, or goiters in patients who are under observation or therapy
Evaluate for recurrence of a thyroid mass after surgery
what is the use of fine needle aspiration biopsy in thyroid nodules
Most important step in the diagnostic evaluation of thyroid nodules
Mean sensitivity higher than 80% and specificity higher than 90%
Can categorize tissue into the following diagnostic categories: malignant, benign, thyroiditis, follicular neoplasm, suspicious, or nondiagnostic
Cost Effective
limitations of fine needle aspiration biopsy
Hypocellular aspirates may be observed in cystic nodules, or they may be related to biopsy technique
The absence of malignant cells in an acellular or hypocellular specimen does not exclude malignancy
Inability to reliably distinguish a benign follicular neoplasm from a malignant neoplasm
Aspirates may be required from multiple sites of the nodule to improve sampling
what is the use of CT in thyroid imaging
lymphadenopathy
local tumor extension
extension into the mediastinum or retrotracheal region
what is the use of MRI in thyroid imaging
Not as sensitive as US in depicting intrathyroid lesions
Helpful in the evaluation of local extension of thyroid neoplasms or the spread of disease into the mediastinum or retro-tracheal region
Mostly incidental
what is the use of NM in thyroid imaging
To determine the size, shape and position of the thyroid gland
• Pertechnetate (99mTcO4) scan
• Iodine-123 scan To assess thyroid uptake function
explain calcium metabolism with regards to the role of parathyroid and parathyroid hormone
Parathyroid and parathyroid hormone play a role in:
- Absorption
- Excretion
- Bone absorption of calcium
Absorption:
-About 10 mmol is absorbed in small intestine, and 5 mmol leaves the body in faeces, netting 5 mmol of calcium a day. It is absorbed across the intestinal brush border membrane under the influence of Vitamin-D
Excretion:
-The kidneys excrete 5 mmol/d. In addition to this, the kidney convert Vitamin-D into calcitriol, which is most effective in intestinal absorption. Both processes are stimulated by parathyroid hormone
what is parathyroid hormone
A peptide hormone that increases plasma calcium. Causes increase in plasma calcium by:
- Mobilization of calcium from bone stripping of calcium from bone, osteoporosis, increase fracture occurrence
- Enhancing renal reabsorption
- Increasing intestinal absorption (indirect)
what is primary hyperparathyroidism?
results from a hyperfunction of the parathyroid glands themselves. There is over secretion of PTH due to adenoma, hyperplasia or, rarely, carcinoma of the parathyroid glands.
what is secondary hyperparathyroidism?
the reaction of the parathyroid glands to a hypocalcaemia (decreased calcium) caused by something other than a parathyroid pathology, e.g. chronic renal failure.
what is tertiary hyperparathyroidism?
result from hyperplasia of the parathyroid glands and a loss of response to serum calcium levels. This disorder is most often seen in patients with chronic renal failure and is an autonomous activity.
what are 5 signs/symptoms of hyperparathyroidism
Weakness and fatigue Depression Bone pain Muscle soreness (myalgias) Decreased appetite Nausea and vomiting, constipation Polyuria, polydipsia Cognitive impairment Kidney stones Osteoporosis
what is the aetiology of hyperparathyroidism
adenoma- 85%
hyperplasia- 10%
ectopic- <5%
carcinoma- <1%
epidemiology of parathyroid glands and adenomas
-About 83% of people have 4 parathyroid glands: 2 superior and 2 inferior glands
-13% have more than 4 glands
-3% have only 3 glands
-The position of the superior glands is usually constant, ectopic sites are often seen with the inferior glands
-Parathyroid adenomas are usually found in the inferior parathyroid gland, however, in 6%-10% of patients, they may be located in:
• the thyroid
• thymus
• the pericardium
• or behind the oesophagus
what is the cause of primary hyperparathyroidism
Parathyroid adenoma
Multiple endocrine neoplasia (MEN) type 1 or type 2a
what is the cause of secondary hyperparathyroidism
Excessive secretion of parathyroid hormone (PTH) by the parathyroid glands in response to:
• hypocalcemia (low blood calcium levels) and/or
• hyperphosphatemia (high blood phosphate levels)
• vitamin D deficiency
what is the cause of tertiary hyperparathyroidism?
long-standing secondary hyperparathyroidism
why do we imaging for hyperparathyroidism?
Detection and localisation of hyper-functioning parathyroid tissue (parathyroid adenoma and parathyroid hyperplasia) in primary hyperparathyroidism
Also used to localise hyper-functioning parathyroid tissue in patients with recurrent or persistent disease
Surgical removal is the only effective means of treatment for symptomatic hyperparathyroidism
It is crucial that parathyroid glands are accurately localised prior to surgery – the success rate of this type of surgery is quite ‘liquid’
what is the treatment and management for hyperparathyroidism
Surgery is the mainstream treatment
what imaging modalities are utilised for the preoperative identification of the site of an adenoma
US
CT
Parathyroid NM study
use of parathyroid US
- Ultrasound is one of the most commonly used initial imaging modalities
- Nodules need to be > 1cm to be confidently seen on ultrasound
- Parathyroid adenomas tend to be homogeneously hypoechoic to the overlying thyroid gland
Use of parathyroid NM subtraction imaging
Subtraction imaging
- An image of the thyroid is obtained using low dose of 99mTcO4 or 123I
- Followed by combined imaging of the thyroid and parathyroid glands using a high dose of 99mTc-MIBI
- The thyroid image is subtracted from the combined image.
Use of parathyroid NM differential washout imaging
- Early and delayed (15 – 20 min and 2 hour post inj.) images are obtained after administration of 99mTcMIBI
- There is faster washout of MIBI from thyroid as compared to thyroid adenoma(s), as the adenomas are hyperactive and contain a greater number of mitochondria
