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Paediatrics RACP written exam > Endocrinology > Flashcards

Endocrinology Flashcards

1
Q

Raised serum C-peptide found in?

A

Obesity

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2
Q

Hypothyroidism can cause…?

A 
Umbilical hernia
Large anterior fontanelle
Poor feeding and weight gain
Small stature or poor growth
Jaundice
Decreased stooling or constipation
Hypotonia
Hoarse cry
Macroglossia
Coarse facial features
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3
Q

Most common CNS cause of precocious puberty?

A

Hypothalamic hamartoma, may be preceded by gelastic seizures

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4
Q

What causes delayed puberty and anosmia?

A

Kallman syndrome - hypogonadotrophic hypogonadism

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5
Q

What conditions are associated with avascular necrosis of the femoral head?

A

Avascular necrosis can be idiopathic or may occur secondary to renal failure, glucocorticoid use, systemic lupus erythematosus, HIV or Gaucher disease.

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6
Q

Describe the features of Cushing’s syndrome

A

Short stature, obesity, hypertension, easy bruising, striae, acne, menstrual abnormalities, proximal muscle weakness (10%)

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7
Q

What are the causes of Cushing’s syndrome?

A

Exogenous steroid therapy is most common cause.
Those not on steroids:
- In young children 50% due to a ACTH-secreting pituitary adenoma and 50% due to adrenal tumours
- After the age of 7 pituitary adenomas account for around 75% of cases

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8
Q

What is the treatment of MODY?

A
  • MODY1 and MODY3 - sulphonylureas

- MODY2 - often does not require treatment, leads to elevated BSL set level.

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9
Q

Describe autoimmune polyendocrinopathy (APECED)

A
  • AR disorder
  • Chronic mucocutaneous candidiasis before progressing to hypoparathyroidism and Addison’s disease
  • Can present with hypocalcaemia
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10
Q

What are the risk factors for developing cystic fibrosis-related diabetes (CFRD)?

A
  • Advancing age (25% by 20y), pancreatic insufficiency, delta F508 mutation, and female gender.
  • Symptoms will include: failure to gain weight; pubertal delay; poor growth; and an unexplained decline in respiratory function.
  • Screen with glucose tolerance test (fasting plasma glucose and HbA1C have low sensitivity )
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11
Q

The enzyme 21 hydroxylase is required for which biochemical step?

A
  • Progesterone to 11 deoxycorticosterone (aldosterone pathway)
  • 17alpha-hydroxyprogesterone to 11-deoxycortisol (cortisol pathway)
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12
Q

What mutation causes 21 hydroxylase deficiency?

A
  • Mutations in the CYP21A2 gene

- Causes >90% of CAH

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13
Q

What are the 3 different causes of CAH?

A
  • 21 hydroxylase deficiency (90%)
  • 11 hydroxylase deficiency
  • 3-beta-hydroxysteroid dehydrogenase type 2 deficiency
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14
Q

What is the main cause of congenital hypothyroidism?

A
  • Thyroid dysgenesis (ectopia, aplasia, or hypoplasia) is the underlying aetiology in 85% of cases
  • Primary hypothyroidism
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15
Q

Why should you treat glucocorticoid deficiency before thyroid deficiency?

A
  • Hypothyroid state reduces cortisol clearance and reduces the metabolic rate
  • Therefore, giving thyroxine prior to treating glucocorticoid deficiency may precipitate an adrenal crisis
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16
Q

What is the mutation in MODY-1 and how do you treat it?

A
  • MODY-1 is due to a transcription factor mutation in HNF4a
  • Treated with sulfonylureas (act by stimulating the production of insulin from the beta cells in the pancreas)
  • Adolescent/early adult onset, progressive
  • Progressive insulin secretory defect
  • May have fetal macrosomia, transient neonatal hypoglycaemia
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17
Q

Describe MODY-2

A
  • AD
  • Present since birth
  • Stable mild fasting hyperglycaemia, max 11-13
  • Mutation in glucokinase (B-cell “sensor”) - reset sensor
  • Usually asymptomatic, usually no treatment required, not progressive, likely underdiagnosed
  • Can have low birth weight is mother doesn’t carry mutation
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18
Q

How do you treat MODY-3?

A
  • Sulfonylureas
  • HNF-1A transcription factor mutation
  • Most common, progressive B cell failure
  • Onset adolescent/early adult, progressive
  • Progressive insulin secretory defect
  • Often normal BSL but high glucose in urine
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19
Q

What are gelastic seizures associated with?

A
  • Hypothalamic hamartomas

- Can lead to precocious puberty

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20
Q

How to distinguish between central and peripheral causes of precocious puberty?

A
  • Peripheral (e.g. CAH and McCune-Albright) are GnRH independent, therefore have a flat GnRH stimulation test (pre-pubertal range)
  • Central (e.g. hypothalamic hamartomas and severe untreated hypothyroidism) are GnRH dependant, therefore have a positive GnRH stimulation test, with inc LH and FSH
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21
Q

What are the causes of cafe-au-lait spots?

A
  • NF1 and NF2
  • McCune Albright syndrome
  • Russell-Silver syndrome
  • Bloom syndrome
  • LEOPARD syndrome
  • Fanconi anaemia
22
Q

What are the findings in Vitamin D resistant rickets?

A
  • Normal or slightly low Ca, mod reduced PO4, no evidence of secondary hyperparathyroidism
23
Q

Effect of maternal hyperparathyroidism on neonatal Ca/ALP/PTH/phos?

A
  • Neonate: low PTH (supressed due to Mum’s high PTH), low Ca, high/normal phos, normal ALP, low Vit D
  • Transient neonatal hypocalcaemia due to maternal hyperparathyroidism
  • Often symptomatic - irritability, poor feeding, seizures, cardiac conduction defects, tetany
24
Q

Effects of parathyroid hormone

A
  • Mobilises calcium from bones
  • Acts on distal renal tubule to increase calcium reabsorption
  • Stimulated 1-a-hydroxylase in kidney to activate Vit D
  • Inhibits renal phosphate reabsorption
  • > inc Ca, decr phos, inc Vit D
25
Q

What is the role of Vitamin D?

A
  • Promotes calcium and phosphate absorption from gut and reabsorption from renal tubules
  • Also causes inc resorption calcium from bones
26
Q

What is the role of calcitonin?

A
  • Released by parafollicular cells of thyroid gland in response to calcium levels
  • Lowers serum calcium by decreasing resorption from bone and increasing renal excretion
27
Q

Most common cause of neonatal hypocalcaemia?

A
  • Maternal diabetes (decr PTH, increased calcitonin, decr maternal Ca+ transfer)
  • However, we don’t actively screen or treat
28
Q

Calcium-sensing receptor defects

A
  • Activating defect shift curve to L - PTH release not triggered at low Ca levels - hypocalcaemia
  • Inactivating defects shift curve to R - PTH inappropriately released at high Ca levels - hypercalcaemia (e.g. familial hypocalciuric hypercalcaemia, AD, usually asymptomatic, low Ca:Creat urinary clearance ratio)
29
Q

Discuss Albright’s Hereditary Osteodystrophy

A
  • Pseudohypoparathyroidism type 1a
  • PTH resistance due to inactivating mutation
  • Short stature, obesity
  • Shortened 3-5th metacarpals, 2-3 toe syndactyly
  • Round face, flat nasal bridge, subcutaneous calcifications, cataracts
  • Paternally imprinted, therefore only inherited from mother
  • Multi-hormone resistance
    • TSH - <2y
    • PTH - infancy or later
    • GHrH - leads to short stature
    • FSH and LH - menstrual irreg in older girls
  • > same mutation inherited from father (maternally imprinted) causes pseudopseudohypoparathyroidism (AHO phenotype but no endocrine dysfunction)
30
Q

Discuss Vitamin D-dependant rickets type 1 and 2

A
  • Type 1: alpha hydroxylase deficiency - cannot produce active form of Vit D
  • Type 2: hereditary vitamin D resistant rickets - mutations in vitamin D receptor - end organ resistance to activated Vit D
31
Q

Discuss X-linked hypophosphatemic rickets

A
  • X-linked dominant, PHEX mutation, FGF23 inhibits phos resorption in kidney, and activation Vit D
  • Most common cause inherited phosphate wasting
  • Low serum phosphate, low active Vit D - low phosphate resorption from gut
  • Osteoarthritis, pseudofractures
  • Rickets, lower limb deformities with short stature, poor growth, poor mineralisation of teeth
  • Ix: high renal phosphate, lowe serum phos and active VitD, inc ALP, normal PTH and Ca
  • Tx: phos supplements in regular doses to avoid peaks - causes hyperparathyroid, calcitriol supp, risk hypercalciuria and nephrocalcinosis, new = burosumab (targets FGF23)
32
Q

Causes of primary hyperparathyroidism?

A
  • Rare in childhood
  • Sporadic due to adenoma
  • Men1 and Men2
  • McCune Albright syndrome
  • > fatigue, abdo pain, nausea, polyuria and polydipsia, depression, renal calculi, pathological fractures
33
Q

Treatment of hypercalcaemia?

A
  • ECG monitoring
  • Hyperhydration, NaCl, loop diuretics - maximise urinary calcium excretion
  • Bisphosphonates, calcitonin - inhibit bone resorption
  • Glucocorticoids - decrease intestinal absorption calcium
  • Dialysis
34
Q

What do the C-cells of the thyroid do?

A

Secrete calcitonin

35
Q

What is the structure of the thyroid?

A
  • Closed follicles which contain central colloid (thyroglobulin - involved in thyroxine synthesis and storage) and surrounded by follicular cells (cuboidal epithelial cells) and C-cells (secrete calcitonin)
  • T3 and T4 stored in colloid, secreted as needed
36
Q

Causes of primary congenital hypothyroidism?

A
  • 85% due to thyroid dysgenesis (problem with structure)
    • Agenesis (did not form at all) or
    • Hypoplasia (2/3rd are ectopic, smaller than usual and abnormal position)
  • Rest are due to dyshormonogenesis (normal structure, problem in thyroxine synthesis) - can be disorder of iodide trapping or T4 production and release
37
Q

Discuss transient neonatal hypothyroidism

A
  • TFTs normalise within months-years, 40% of CH
  • Still important to start treatment, then stop at age 3-4yrs and recheck TFTs after 1 month to see if still stable
  • Causes:
    • Maternal antithyroid meds
    • Prenatal or postnatal iodine
    • Maternal TSH receptor blocking antibodies (no uptake on radioisotope scan) - resolves by 3-6m
    • Prenatal exposure to maternal hyperthyroid
    • Prematurity esp <27/40
    • Drugs: steroids, dopamine
38
Q

Discuss Grave’s disease

A
  • Stimulating antibodies to the thyrotropin receptor (TSHR-Ab)
  • High T3 and T4, low TSH
  • Usually early puberty
  • ADHD like symptoms, goitre, exophthalmos, acceleration of growth
  • Tx: antithyroid drug 1st line (carbimazole > PTU as more side effects with PTU. Inhibits thyroid peroxidase). Remission rates 35-65%.
    2nd line = surgery or radioactive iodine (no inc risk malignancy).
39
Q

Neonatal hyperthyroidism

A
  • 2% of maternal Grave’s disease
  • TSH receptor stimulating antibodies (still present even if maternal thyroidectomy)
  • Baby restless, tachy, irritable, anxious, alert, exophthalmos
  • Remits by age 3-4m but need treatment in meantime to dec risk microcephaly and ID, heart failure
  • Tx: carbimazole
40
Q

Discuss subacute thyroiditis

A
  • Quervain Disease
  • Painful swelling of thyroid gland, follows URTI
  • High fever, unilateral swelling of gland, suppurative thyroiditis
  • Due to release or preformed thyroid hormones
  • High ESR, low TSH, thyroid antibodies -ve, absent radioactive uptake
  • Acute phase 2-6/52, pain, mild hyperthyroidism -> hypothyroid phase, permanent in 10%, recovery wks-mths
41
Q

Discuss Pendred Syndrome

A
  • AR, sensorineural deafness, 50% have hypothyroidism
  • Mutations in pendrin which is needed for transport of iodide across apical membrane of follicular cell into colloid space
  • Show only a partial discharge of iodide with thiocyanate or perchlorate
42
Q

Discuss sick euthyroid

A
  • Change in serum thyroid function associated with acute illness
  • Protective: prevents catabolism
  • Stages: 1 - decr T3, 2 - decr TSH, 3 - decr T4, 4 - resolution with modest inc TSH, normal T3 and T4
  • No benefit in treating as resolves
43
Q

Describe the hormone production in the adrenal glands

A
  • Cortex:
    • Glomerulosa - aldosterone
    • Fasciculata - cortisol
    • Reticularis - Androgens
    • (GFR - salt, sugar/stress, sex)
  • Medulla - Epinephrine, norepinephrine
44
Q

What is the difference between 11-beta hydroxylase and 21-hydroxylase deficiency?

A

In 11-beta hydroxylase deficiency you don’t get salt wasting. Get hypertension due to salt retention due to inc deoxycorticosterone. Also deoxycortisol has reasonable cortisol function

45
Q

Causes of pheochromocytoma?

A
  • Sporadic, SDHx mutation (succate dehydrogenase mutation) or SDHB gene - risk of paragangliomas
  • MEN 2
  • NF1
  • Von Hippel Lindau
46
Q

Where do LH and FSH act?

A

Males:

  • LH - leydig cells - testosterone
  • FSH - sertoli cells - spermatogenesis

Females:

  • LH - lutein cells - progesterone + androgens
  • FSH - granulosa cells - oestrogen
47
Q

Autoimmune polyglandular syndrome type 1 consists of?

A
  • Addison’s disease (early adolescence)
  • Chronic mucocutaneous candidiasis (1st manifestation)
  • Hypoparathyroidism
  • Other associations: Primary hypogonadism, malabsorption, chronic active hepatitis, keratopathy, enamel hypoplasia, nail dystrophy, vitiligo, alopecia, juvenile gastritis +/-pernicious anaemia.
48
Q

Autoimmune polyglandular syndrome type 2 consists of?

A
  • Addison’s disease &
  • Primary hypothyroidism (Chronic Lymphocytic Thyroiditis)
    OR
  • Type 1 diabetes
  • Other associations: vitiligo, primary hypogonadism, alopecia, adult gastritis +/-pernicious anaemia.
49
Q

Precocious and delayed puberty timings

A
  • Girls precocious <8, delayed > 13

- Boys precocious <9, delayed > 14

50
Q

Criteria for diagnosis of diabetes?

A

Random BSL >11 or fasting BSL >7
+ classic symptoms diabetes
+ HBA1c >6.5%

51
Q

MEN 1

A

Pancreatic (gastrinoma, insulinoma), pituitary tumours, hyperparathyroid. Werner syndrome

52
Q

MEN 2A + MEN 2B

A
  • 2A: medullary thyroid cancer, parathyroid, pheochromocytoma. Sippley syndrome
  • 2B; thyroid, pheochromocytoma, Marfinoid habitus, mucosal neuromas, skeletal abnormalities. Wagenmann-Froboese syndrome

Paediatrics RACP written exam (18 decks)

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