Endocrinology Flashcards
Anterior Pitutary hormones
GH
TSH
FSH
LH
ACTH
Prolactin
Posterior Pitutary hormones
Oxytocin
ADH
Posterior pitutary hormones are produced by itself. T/F?
No
Hormones are produced by the hypothalamus. They are released by the posterior pitutary.
Hormones produced by the adrenal galnds
Glucocorticosteroids - Cortisol
Mineralocorticosteroids - Aldosterone
Androgens - Sex hormones
What are the main endocrine glands?
Hypothalamus
Pitutary gland
Thyroid
Parathyroid
Liver - IGF
Adrenal
Kidney - Renin, EPO
Testes
Uterus - Prolactin
Ovary
Pancreas - Insulin, glucagon, somatostatin
Stomach - Gastrin
Thymus
Causes of congenital hypothyroidism
Mal descent of the thyroid and thyroid dysgenesis (Commonest)
Dyshormonogenesis, an inborn error of the thyroid hormone synthesis.
Iodine deficiency.
Early recognition of congenital hypothyroidism is very important. Why?
Early recognition (within 3M of birth) is very important because Congenital Hypothyroidism is one of the few preventable causes of severe learning difficulties.
Delayed Rx will not prevent mental deficiency.
C/F of Congenital Hypothyroidism
Usually asymptomatic, picked up on screening.
Failure to thrive
Feeding problems
Prolonged Jaundice
Constipation
Pale, cold and mottled skin - Due to poor peripheral blood circulation, due to reduced HR
Coarse facies
Large tongue
Hoarse cry
Goitre (occassionaly)
Umbilical hernia
Delayed development
Ix for congenital hypothyroidism
T3, T4 - Decreased
TSH - Increased
TSH also decreased in central hypothyroidism
USS - Neck (Whether thyroid gland is present)
TSH test is done with venous blood sampling at 3-5 days of life. If done before 3 - 5 days, may give abnormal result due to maternal thyroxine.
Heel prick test - Prick either side of heel, blot with filter paper. Allow to dry and send to lab. Capillary TSH level can be done before discharge.
If capillary TSH is high, Venous TSH test should be done.
If Venous TSH levels take 1-2 days, Rx can still be started. One +ve test is. enough to begin Rx.
Congenital hypothyroidism Mx
Early Rx (within 3M) is essential to prevent learning difficulties.
Rx is lifelong with oral Thyroxine, titrating the dose to maintain normal growth, TSH and T4 levels.
Thyroxine is given as a tablet in the morning on an empty stomach.
How is the treatment for congenital hypothyroidism deemed adequate?
Normal growth (bone age becomes normalized) with height gain specially
Development and cognition becomes normal.
Sx improvement - Eg: bradycardia and constipation
T3, T4, TSH within normal range.
What is the cause for jaundice in hypothyroidism?
Thyroxine is required for conjugation of bilirubin.
C/F of acquired hypothyroidism
Females > Males - Because female thyroxine or hormone demand is high. Especially in puberty.
Short stature/ growth failure
Delayed bone age
Cold intolerance
Dry Skin
Cold peripheries
Bradycardia
Thin, Dry hair
Pale, puffy eyes with loss of lateral eyebrows
Goitre (may also be physiological in pubertal girls)
Slow - relaxing reflexes
Constipation
Delayed puberty/Early puberty
Obesity
Slipped Upper femoral Ephiphysis (SUFE)
Deterioration in school work
Learning difficulties
Acquired hypothyroidism Mx
Ix - TSH level increased, T3 and T4 levels decreased.
Rx is with thyroxine - Not life long.
If an autoimmune disease is suspected, antibody testing also should be done.
C/F of Hyperthyroidism
Anxiety, restlessness
Increased appetite
Sweating
Diarrhea
Weight loss
Rapid growth in height
Advanced bone maturity
Tremor
Tachycardia (Can lead to arrythmia)
Wide pulse pressure
Warm, vasodilated peripheries.
Goitre (Bruit)
Learning difficulties/behavior problems
Psychosis
Benign Murmur (Functional) - Due to hyper-dynamic circulation.
Eye signs (uncommon in children):
Exophthalmos
Ophthalmoplegia - abnormal eye movements
Lid retraction
Lid lag
Causes of hyperthyroidism in children
Usually results from Graves disease (autoimmune thyroiditis) - Antibodies bind to thyroid receptors stimulating thyroxine production.
Hyperthyroidism Ix
T3, T4 levels elevated
TSH suppressed to very low levels.
Antithyroid peroxisomal antibodies may also be present.
Hashitoxicosis
Continous thyroid stimulation leads to thyroid cell death which in turn causes hypothyroidism
Hyperthyroidism Rx
Congenital hyperthyroidism settles on its own, after maternal antibodies deplete, within about 3M.
First line rx is medical, with drugs such as carbimazole or propylthiouracil that interfere with thyroid hormone synthesis.
Initially, Beta blockers (proponalol) and be added for Symptomatic relief of anxiety, tremor and tachycardia.
Medical Rx is given for about 2 years, which should control the thyrotoxicosis, but the eye signs may not resolve.
When Medical rx is stopped, 40-75% relapse.
A second course of drugs maybe then be given or subtotal thyroidectomy will usually result in permenant remission.
Radioiodine Rx is simple and is no longer considered to result in later neoplasia.
Follow up is required as thyroxine replacement is often needed for subsequent hypothyroidism.
S/E of hyperthyroidism Rx
Risk of neutropenia specially with carbimazole.
All families should be warned to seek urgent help and a blood count if sore throat and high fever occur on starting Rx.
Causes of Neonatal hyperthyroidism
May occur in infants of mothers with Graves disease from the trans placental transfer of Thyroid stimulating Immunoglobulins (TSI).
C/F of neonatal hyperthyroidism
Tachycardia
Sweating
Irritability
Poor weight gain
Failure to thrive
Complications of Neonatal hyperthyroidism
Tachycardia
SVT
HF
Mx of Neonatal hyperthyroidism
Resolves spontaneously with time
Cardiac arrhythmias and HF should be managed accordingly.
Some children will need antithyroid drugs such as carbimazole.
Definition of puberty
Transition from a child to an adolescent
What results in Puberty?
GnRH pulsatile secretion
Sequence of Puberty in F and M
In females,
1st Breast - Thelarche. 8 - 12 years
Pubic hair - Pubarche. Occurs immediately after breast development.
Bleeing - Menarche. After 2.5yrs after puberty starts.
In Males,
1st Testis enlargement (>4ml) - After 9 years
Pubic hair - Between 10-14yrs
voice deepening
Height spurt - When the testicular volume is 12-15ml. After a delay of around 18M.
Height gain first starts in females (about 9-10yrs). Early end too. 11 - 12yrs in males.
How is male testis enlargement measured?
Using an orchidometer.
Tesits is palpated using one hand, and the orchidometer with the other.
Usually an endocrinologist conducts this.
What is stereognosis?
Ability to decide size by just palpating.
Changes in Puberty
In both sexes,
Acne, axillary hair, body odor and mood changes - Irritability, depression, attraction to the opposite sex.
Further assessments if puberty is abnormally late or early.
Bone measurement from a hand and wrist x-ray to determine skeletal maturation.
Early Puberty - advanced bone age.
Late puberty - Delayed bone age
In females, pelvic USS to assess uterine size and endometrial thickness.
What is precocious puberty?
The development of secondary sexual characteristics before 8yrs old in females and 9yrs old in males is defined as outside the normal range.
Cut-off age for precocious puberty in M & F
Males - <9Yrs
Females - <8yrs
Types of Precocious puberty
When it is accompanied by a growth spurt
Premature breast development
Premature Pubic hair development
If onset is early - maybe familial (specially in females)
If breast/pubic hair w/o height spurt - Unlike to go into menarche
If with a height spurt - Likely to go into menarche and full puberty
What is the difference between True/central and pseudo/Peripheral precocious puberty?
Central - GnRH dependant from premature activation of the hypothalmic-pitutary-gonadal axis.
Normal physiological order will be followed. Breast, Hair, bleeding.
FSH/LH will be high, Height spurt will be present.
Pseudo/ Peripheral - GnRH independant. From excess sex steroids.
Height spurt might not occur. One or two will be present (Breast, Hair and bleeding, etc.)
Causes of Precocious Puberty
In males, Usually an organic cause. Is a brain tumor until proven otherwise. Uncommon.
In females, usually idiopathic or familial (FHx in mother/grandmother) and follows normal sequence of puberty. Organic causes are rare.
A 4yr old boy presents with testes of 6ml volume. To differentiate between central or peripheral precocious puberty, what is the next step?
Assess for height spurt.
How can Testes examination be helpful in determining central or peripheral precocious puberty (PP)?
B/L small testes + Axillary hair - Peripheral PP + adrenal cause (a Tumor or adrenal hyperplasia)
Unilateral enalarged testis + axillary hair - Peripheral PP + Gonadal tumor (Testicular tumor)
B/L enlarged testes + Axillary hair - True PP. Intracranial Lesion.
Tumors in the hypothalamic region are best Ix by crainal MRI scan.
Precocious Puberty Mx
Detection and Rx of underling pathology - Ovarian and testicular tumors
Addressing psychological/ behavioral difficulties
GnRH analogues - Goseralin/Zoladex - Keeps GnRH levels constantly high. Prevents pulsatile secretion.
When child is ready to achieve pubertal age, GnRH therapy can be stopped. - Eg: Asking mother about other children in the class.
Zoladex is given as S/C injection.
Why is it necessary to delay onset of puberty?
Socially unacceptable
Ultimate Height less - Child will be short as an adult. Growth plates will fuse early.
How many stages of breast development is there?
5 Stages
4 and 5 are adult breasts