Endocrinology and Metabolic Medicine Flashcards
What are the hypothalamic releasing and inhibiting factors?
Releasing: GnRH GHRH TRH CRH Inhibiting: Somatostatin Dopamine
Which releasing factors act on the anterior pituitary and what do they cause to be released or downregulated?
GnRH - LH and FSH which acts on the gonads to produce androgens
GHRH - GH acts on liver to cause growth via Insulin-like GF
TRH - releases TSH, causing the thyroid to release thyroxine
Somatostatin - down-regulates GH and TSH release
Dopamine - down-regulates prolactin release
CRH - ACTH release causes steroid synthesis in the adrenals
What hormones are released by the posterior pituitary
vasopressin - renal tubules
oxytocin - breasts and uterus
Symptoms of over-production in the pituitary
Acromegaly - prognathism, interdental separation, large tongue, spade-like hands and feet, tight-fitting rings, or gigantism in children
Prolactin excess - galactorrhoea, gynecomastia
ACTH excess - nelson’s (hyperpigmentation, visual disturbance, headaches, menstrual cycle disturbance) or Cushing’s (weight gain, central fat distribution, abdominal striae, hirsutism, mood changes, gonadal dysfunction)
Local effects of pituitary tumours
bitemporal hemianopia
cavernous sinus infiltration - III (ptosis, lateral gaze), IV (diplopia corrected with head tilt) and VI (lateral rectus palsy) cranial nerve palsy
Bony or meninges infiltration - headaches
hypothalamus infiltration - obesity, precocious puberty
ventricular infiltration - hydrocephalus
what is the short synACTHen test?
ACTH analogue is given, which should stimulate cortisol secretion
measure plasma cortisol should rise to over 500nmol/L
A negative response suggests primary hypoadrenalism (Addison’s)
What is an insulin tolerance test?
2 CIs
measures growth hormone response
can assess pituitary reserve
CI IHD and epilepsy
What is a dexamethasone suppression test?
dexamethasone should suppress ACTH and cortisol
failure to suppress suggests cortisol excess - Cushing’s
symptoms of hypopituitarism
gonadotrophin deficiency: loss of libido, erectile dysfunction, amenorrhoea Hyperprolactinaemia: galactorrhoea, hypogonadism GH deficiency: Short stature in children, no effect in adults Hypothyroidism and adrenal failure: TATT, weight gain, slow, depression.
Causes of hypothyroidism (5)
Primary:
primary atrophic hypothyroidism (common) - no goitre
Hashimoto’s thyroiditis - immune infiltrate causes goitre
Iodine deficiency - rare in UK due to water supplementation
Iatrogenic - surgery, radioiodine treatment, amiodarone, lithium, iodine
postpartum or De Quervain’s thyroiditis - painful goitre
Secondary: v rare due to hypopituitarism
Causes of hyperthyroidism (6)
Graves - common, immune infliltrate causes goitre
toxic multinodular goitre - older, iodine deficient patients. decompressive surgery.
toxic adenoma - solitary overactive nodule
ectopic thyroid tissue - Metastatic thyroid cancer or teratoma
iodine or thyroxine excess
thyroiditis - postpartum, due to amiodarone
ECG changes in myoxoedemic crisis
heart block, prolonged QT, ST and T wave changes
adrenal layers and their hormones
zona glomerulosa - mineralocorticoids - fluids - Na retention, salivary glands, sweat, colon, BP
Zona fasiculata - glucocorticoids - anti-inflammatory, promote glouconeogenesis, lipolysis and inhbit glucose uptake
Zona reticularis - androgens - secondary to gonads
Adrenal medulla- catecholamines - sympathetic nervous system
Adrenal excess - name and causes (7)
cushing’s syndrome
ACTH dependent
-pituitary disease - cushing’s disease
-ectopic ACTH - small call and carcinoid tumours
-ACTH administration
ACTH independent causes
-adrenal adenomas
- adrenal carcinomas
- glucocorticoid administration (MOST COMMON)
Alcohol-induced psuedo-cushing’s syndrome
symptoms of Cushing’s (7)
central obesity +/- buffalo hump plethoric complexion thin, easily bruising skin striae on the abdomen, legs, breasts proximal myopathy pathological # hypertension
what is Addison’s disease?
adrenal insufficiency due to autoimmune destruction of the adrenal cortex. May also be due to TB, surgical removal of adrenals or malignant infiltration.
Symptoms of Addison’s
lethargy, depression, anorexia, weight loss
postural hypotension and salt craving
hyperpigmentation in skin folds
vitiligo and hair loss in women
symptoms of Addisonian crisis
vomiting abdominal pain profound weakness hypoglycaemia hypovolaemia
management of Addisonian crisis (5)
take cortisol and ACTH, calcium and other bloods give 100mg IB hydrocortisone give fluids - saline treat hypoglycaemia treat precipitating cause
Primary hyperaldosteronism presentation and causes
hypertension, hypernatraemia, and hypokalemia
adrenal hyperplasia
adrenal adenoma
adrenal carcinoma (rare)
diagnostic criteria for diabetes
present once if symptomatic, twice if asymptomatic.
Fasting BM - 6.0 to 7.0 = prediabetse, >7.0= diabetes
HBA1C 41 to 48 = prediabetes, >/=48 = diabetes
DKA management
Fluids
fixed rate insulin infusion 0.1u/kg/hr and usual long-acting insulin
Causes of thyroid storm (4)
thyroid or non-thyroidal surgery
trauma
infection
acute iodine load e.g. CT contrast media
presentation of thyroid storm (7)
fever > 38.5ºC tachycardia confusion and agitation nausea and vomiting hypertension heart failure abnormal liver function/jaundice
management of thyroid storm (6)
symptomatic treatment e.g. paracetamol
treatment of underlying precipitating event
IV propranolol
anti-thyroid drugs: e.g. methimazole or propylthiouracil
Lugol’s iodine
dexamethasone - e.g. 4mg IV qds - blocks the conversion of T4 to T3
Phaeochromocytoma
what is it?
associations
catecholamine secreting tumour 10% are familial - associated with MEN type II, neurofibromatosis and von Hippel-Lindau syndrome 10% are bilateral 10% are malignant 10% are extra-adrenal
symptoms of phaeochromocytoma (5)
hypertension
episodic palpitations, anxiety, sweating, headaches
diagnostic test for phaeochromocytoma
24hr urinary metanephrines
Mx of phaeochromocytoma
surgery is definitive Mx
alpha then beta-blocker to control hypertension until then
What is SIADH?
hyponatraemia secondary to excessive water retention
causes of SIADH (5 categories)
Brain injury - stroke, SAH, subdural, infection
Malignancy- SCLC
Infections - TB, pneumonia
Drugs - SSRIs, TCAs, carbamazepine, sulfonylureas, vincristine, cyclophosphamide
Hypothyroidism
Mx of SIADH
slowly replace Na to prevent central pontine myelinolysis
Fluid restriction
drugs - ADG receptor antagonisits
MEN I
Three Ps
Parathyroid (95%): hyperparathyroidism due to parathyroid hyperplasia
Pituitary (70%)
Pancreas (50%): e.g. insulinoma, gastrinoma (leading to recurrent peptic ulceration)
Also: adrenal and thyroid
Commonly present as hypercalcaemia
MEN II
Medullary thyroid cancer (70%) 2 P's Parathyroid (60%) Phaeochromocytoma RET Oncogene
MEN III
Medullary thyroid cancer
1 P
Phaeochromocytoma
Marfanoid body habitus
Neuromas
RET Oncogene
A second drug should be added in type 2 diabetes mellitus when?
HbA1c is > 58 mmol/mol
hypoglycaemia with reduced GCS Mx
give 100ml 20% IV Glucose if there is access
What is gastroparesis
GI autonomic neuropathy often due to diabetes
erratic blood glucose control, bloating and vomiting
management options include metoclopramide, domperidone or erythromycin (prokinetic agents)
oral hypoglycaemic choice in T2DM
start with metformin and titrate dose accordingly
if not adequeate
add a gliptin if obese
if not add a sulfonylurea if not (glicazide)
ECG changes in hypocalcaemia
Common: Corrected QT interval prolongation
Rare: Atrial fibrillation or torsade de pointes
