Endocrine Flashcards
Blood supply of thyroid
Superior thyroid- branch of external carotid
Inferior- thyrocervical
Thyroidea ima- from brachiocephalic
Venous supply of thyroid
Superior and middle- IJV
Inferior in brachiocephalic
Synthesis of thyroid hormones
- Thyroid actively concentrates iodide( to 25 times the plasma conc.)
- Iodide is oxidised to atomic iodine by peroxidase(in the follicular cells)
- Atomic iodine then iodinates tyrosine residues (contained in thyroglobulin).
- Iodinated tyrosine residues undergo coupling to either T3 or T4.
- Process is stimulated by TSH, which stimulates secretion of thyroid hormones.
AB in hasimotos
Thyroperoxidase
Most sensitive tests for hyper and hypo thyroidism
Hyper- T3
Hypo- TSH and T4
Features of toxic nodule
Small swelling @midline/near midline; hot intolerance recently
Low TSH
High T3
What is suggestive of a thyroid cancer on imagine
Cold nodule- reduced/no uptake in radio iodine
Causes of hypothyroidism
Primary-Hashimoto
Iodine def
Radioiodine
Secondary- pituitary- surgery, tumour, radiation
Tertiary- hypothalamus
Pendred syndrome
Bilateral sensorineural hearing loss + Goitre + Hypothyroidism
Cause of brown tumour
Brown tumors are tumors of bone that arise in settings of excess osteoclast activity, such as hyperparathyroidism
They appear brown because haemosiderin is deposited at the site.
Mx of severe hypercalcaemia
Aggressive fluids
IV pamidromate
Furosemide
When is urgent mx of hypercalc required
> 3.5
Reduced consciousness
Abdo pain
Pre Renal failure
Causes of hypocalcaemia
Vit D def
Renal failure
Hypoparathyroidism
Pseudohypo (target insensitive to PTH)
Mg def
Sx of hypocalacaemia
Parasthesia
Spasm, tetany, convulsion
Psychosis
Chcosteck
Trousseau
Prolonged QT
Mx of severe hypocalcaemia
Calcium gluconate, 10ml of 10% solution over 10 minutes
What is Mg required for physiologically
Mg is required for both PTH secretion and its action on target tissues.
- Hypomagnesaemia cause both hypocalcaemia and make patients unresponsive to treatment with calcium and
vitamin D supplementation.
Most common cause of hyponatraemia in surgery
Over administration of dextrose
Causes of pseudohyponatraemia
Include hyperlipidaemia (increase in serum volume)
Multiple myeloma
Taking blood from a drip arm
Features of papillary thyroid cancer
Young person
Multinodular
Not capsulated
Orphan Annie nuclei
Psammoma body
TSH dependent
Spread by lymphatics !
Cold radioisotope
Features of follicular thyroid cancer
Capsulated
Solitary nodule
Spread via blood- to lung, brain, bone
Prominent oxyphil cells and scanty thyroid colloid
Features of medullary thyroid cancer
Multifocal- MEN
Diarrhoea and flushing
Potentially recurrent after surgery
High calcitonin- para C cells
Features of anaplastic thyroid cancer
Rapidly enlarging
Aggressive
Local invasion
Cold scan
Mx of thyroid cancer
Pap
<2cm lobectomy
Thyroxine life long
Yearly thyroglobulin FU
> 2cm
Total thyroidectomy
RI ablation
Suppressive thyroxine lifelong
Yearly TG FU
Follicular- total
Adenoma- hemi
Med
Total thyroidectomy
Thyroxine
Yearly FU calcitonin
Anaplastic
Debulking and radio palliation- isthmusectomy
Total + radio if capsule and no evident mets
Lymphoma
Radio +/- chemo
Features of lymphoma of thyroud
Hx of Hashimoto
Rapidly enlarging
B cell
Type of follicular cancer with poor prognosis
Hurthle cell cancer
Acute thyroiditis features
Euthyroid
Fever
High ECC
Sub acute thyroiditis - De querveins
Granulomatous
Hyperthyroidism then hypo
High WCC
High T4 low TSH
SMooth tender thyromegaly
Low uptake on scan
Hashimoto features
TPO +
TG+
Anti mito
TSH receptor
Firm hard receptor
Cold, weight gain, tired
Reidel syndrome
Hypothyroid
Hard
AB -ve
Fibrosing
Cold nodule with hyperthyroid symptoms
Thyroid Carcinoma associated with Grave’s disease is usually Papillay
Mx of Graves disease
Medical
1st Carbimazole - TPO inhibitor
2nd Propylthiouracil -use in pregnancy
Radio - small, no eye
Surgery - large, eye sign
Must be euthyroid and vocal cord exam before surgery
Mx of multinodular goitre
Total thyroidectomy
Mx of thyrotoxicosis with eye signs
Carbimazole
Then if relapse- total thyroidectomy
High TSH and normal/high T4
Poor complience of thyroxine
Low TSH and normal T4
Steroid therapy
Skin features of hypothyroidism
Dry- anhydrosis
Non pitting edema
Eczema
Xanthomata
Skin features of hyperthyroidism
Pretibial myxoedema
Acropachy- clubbing
Sweating
Radioiodine
Close contact with children not permitted for 4 weeks
15% with eye signs get worse
Symptoms improve after 6-8w
80% become hypothyroid
CI in pregnancy
Prolactinoma sx
Nipple discharge
Gynaecomastia
Visual signs
Causes of gyanecomastia
Kallman
Kleinfelter
Test failure
Spironolactone- most common
Finasteride
Anabolic steroids
Oestrogens
When is IV bisphosphante require
Ca >3
FHH sx
Loss of PTH receptor sensitivity found in parathyroid and kidney
Parathyroid- doesn’t detect- increase/normal PTH- Mild hypercalcaemia
Kidneys- meant to inhibit reabsorption but doesn’t- hypocalciuria
High Mg
Indications of parathyroidectomy
ABCS
<50 age, Asymptomatic - Ca 1 above normal
BMD <2.5 SD
Calciumstones Nephrolithiasis
Life threatening hypercalcaemia
Symptomatic
Pseduohypoparathyroidism
G protein abnormailty- insensitive to PTH
Low IQ, short stature, 4/5th metacarpal short
Low Ca, high phosphate, high PTH
Measure urinary cAMP and phosphate following PTH infusion
If increases- hypoparathyroidism
If no- Pseudo
Psuedopseduohypoparathyroidism
Skeletal defects similar to PHPTH
Normal biochem
Thyroid cancer linked to prolonged irradiation exposure
Papillary
Adrenal mass that has a lipid rich core
Adenoma
Cells of phaeo
Chromaffin cells
10% rule of phaeo
10% of cases are bilateral.
10% occur in children.
11% are malignant (higher when tumour is located outside the adrenal).
10% will not be hypertensive.
Post thyroidectomy- patient becomes profoundly dyspneic and hypoxic
Tracheomalacia
If ultrasound shows indeterminate mass in breast and FNA shows normal tissue what should you do
Excisions biopsy
CT rarely helpful in breast
Patient presents with MSK pain and x rays show widespread osteopenia -waht ix
USS of neck
Cell changes in tertiary hyperparathyroid
Hyperplasia of all 4 glands
Haemorrhage in adrenal glands
Waterhouse - Friderichsen syndrome
Thyrotoxicosis, proptosis- receives radiotherapy on eyes, symptoms relapse after stopping carbimaozle
Tx?
Total thyroidectomy
After thyroidectomy pt develops oculogyric crisis and muscle spasm
hypocalcaemic tetany and will require immediate calcium supplementation.
Psychiatric drug that can cause thyroid goitre
Lithium
FNA vs core biopsy
Core biopsy is preferred over FNAC by most surgeons.
The reason for this is that FNAC often yielded inadequate tissue for assessment.
When FNAC demonstrated benign changes, it had to be repeated at least once to confirm this.
If it yielded cells that were indeterminate, then a core biopsy was needed.
A core biopsy removes many of these stages and is thus more reliable.
Thyroglossal cyst removal
Resection of cyst
Associated track
Central portion of hyoid and wedge of tongue
Sistrunks procedure
Thyroid mass, euthyroid Ix?
FNAC
Other AB found in hashimotos
Anti microsomal
Proportion of primary HPTH caused by adenoma
85%
% of patient with HPTH that are symptomatic
30%
Area affected in adrenals in addisions
Fasciculata
Ig of Anti TSH
IgG
Treatment of Graves in Pregnancy
PTU in first
Can do carbimazole after
Treatment success of anti thyroid drugs in children
1/3 replase
Dex suppression test results
Cortisol raised- adrenal adenoma or bronchial
If ACTH high small cell
If Low adrenal
If cortisol suppressed pituitary- usually with high dose
Which thyroid cancer has best prognosis
Papillary
Dx of acromegaly
Initially by IGF 1
Then oral glucose with lack of suppression of GH <1 measurements
Diagnosis of diabetes and pre diabetes
Fasting
6.1 7.1
Random
7.8 11.1
Hba1c
42 48
Problems with stopping antithyroid drugs
High recurrence rates
Where globally is incidence higher for follicular cancer
Iodine deficient
Common extra adrenal location of phaeo
Organ of Zuckerkandl
Aortic bifurcation
Proportion of medullary thyroid that is familial
20%
Other conditions Hashimotos is associated with
Coeliac and pernicious anaemia
And other AI
FHH inheritance and electrolyte disturbances
AD
Hypermagnesium
Specific imaging for phaeo
MIBG
Top endogenous cause of cushings
Pituitary adenoma
Proto oncogene with MEN
RET
Bilateral adrenalectomy now developed bitemproal semi, pigmentation
Nelsons syndrome
Expanding pit tumour- high ACTH
What electrolyte abnormality suggests chronic renal failure
Low Ca
Thyroid effect on fat
Hypothyroid hypercholestrol
Initial test for phaeo
VMA/HVA 24 hour urine
Conditions phaeo is associated with
MEN 2A+B
VHL
NFM1
Best method of localised parathyroid adenoma
Bilateral neck exploration
Bilateral hilar lymphadeopathy with high Ca
Sarcoid
Thyroid effects on Ca
Hyper high Ca
Liddle syndrome
Hypokalaemia metabolic acidosis with HTN
Low renin activity
AD
Resistant HTN
Gieltman syndrome
Hypokalaemia metabolic alkalosis
Hypocalciuria and hypomagnesia
BP normal or low
Def in Na/Cl in DCL
Phaeo, medullary and itchy lesions
MEN 2A
Itchy lesions are cutaneous lichen amyloidosis
Pre op parathyroid localisation
US
Sestamibi radionucleotide scan
Technetium
Most useful initial ix of goitres
US and FNA
Thiazides on Ca
Hypercalcaemia - mild
Which thyroid cancer associated with radiation
Papillary
Most common enzyme def in CAH
21
