Diabetes + pituitary Flashcards
Diabetes
What is diabetes insipidus?
Inadequate secretion or insensitivity to vasopressin, causing hypotonic polyuria
What is the vasopressin pathway?
ADH is created in the hypothalamus
ADH is secreted in the posterior pituitary
ADH binds to the kidney and increases water reabsorption
Urine osmolality is raised
Serum osmolality is decreased
What are the two types of diabetes insipidus?
Cranial
Nephrogenic
What are the causes of cranial DI?
Posterior pituitary fails to secrete ADH
Due to: pituitary tumour, infection, sarcoidosis
What are the causes of nephrogenic DI?
Collecting ducts insensitive to ADH
Hypocalcaemia, hyperkalaemia, lithium, inherited (AVPV2 gene), idiopathic
What is the presentation of DI?
Polyuria
Nocturia
Polydipsia
Lethargy/irritability/confusion (high Na)
What are the investigations for DI?
U+E
Glucose
Water deprivation test
What happens during water deprivation of a normal Pt?
Urine becomes concentrated
osm >600
What happens during water deprivation of a Pt with cranial DI?
Kidneys are unable to concentrate the urine
osm <400
What happens during water deprivation of a Pt with nephrogenic DI?
Kidneys are unable to concentrate the urine
osm <400
What do you give a Pt for the second part of the water deprivation test?
Desmopressin
What happens when you give desmopressin to a Pt with cranial DI?
Urine osm raises by >50% after desmopressin
What happens during water deprivation of a Pt with nephrogenic DI?
Urine osm raises by <45% after desmopressin
What is the management for DI?
Treat the cause eg.
Cranial- intranasal desmopressin
Nephrogenic- thiazide diuretic or NSAIDs
What is T1DM?
Hyperglycaemia due to a deficiency of insulin production (90% autoimmune destruction of B cells)
What is T2DM?
Hyperglycaemia due to a resistance to insulin action
What is the presentation of T1DM?
Polydipsia
Polyuria
Tired/weight loss
DKA
What are the clinical features of a DKA?
N+V
Kussmaul breathing
Ketone breath
Abdo pain
What is the presentation of T2DM?
Polydipsia
Polyuria
What are the risk factors for T1DM?
HLA DR3/4
Other autoimmune conditions
What are the risk factors for T2DM?
Obesity FHx Ethnicity Endocrine Drugs
How is diabetes mellitus diagnosed?
Blood glucose measurement
Fasting >= 7.0mmol/L
Random > 11.1mmol.L
What is the management for T1DM?
Insulin
Patient education
What is the management for DKA?
Fluids
What is the management for T2DM?
Diet and lifestyle
Metformin/sulphonylurea/insulin
How can you categorise hyponatraemia?
Hypovolaemia
Euvolaemia
Hypervolaemia
What are the causes of hypovolaemic hyponatraemia?
Diarrhoea
Vomiting
Diuretics
What are the causes of euvolaemic hyponatraemia?
Hypothyroidism
Hypoadrenalism
SIADH (pneumonia, cancer)
What are the causes of hypervolaemic hyponatraemia?
HF
Cirrhosis
Nephrotic syndrome
What are the signs of hypovolaemic hyponatraemia?
Reduced turgor
Postural hypotension
Dry mucous membranes
What are the signs of hypervolaemic hyponatraemia?
Oedematous
High JVP
What are the investigations for hypovolaemic hyponatraemia?
Urine sample
-low Na as body tried to retain Na due to hypovolaemia
What are the investigations for euvolaemic hyponatraemia?
TFTs
synACTHen test
Drug review, breast exam, CXR, brain MRI
What should you do if a Pt is severely hyponatraemic?
Give slow hypertonic saline
What should you be careful for when giving a Pt hypertonic saline and why?
Do not exceed 10mmol/L in the first 24h
Risk of central pontine myelinosis
What are the complications of hyponatraemia?
Seizures
Decreased consciousness
What are the causes of hypernatraemia?
Vomiting Diarrhoea Burns Diabetes insipidus Primary hyperaldosteronism (Conn's)
What is the presentation of hyponatraemia?
MILD: nausea, vomiting, headache, anorexia and lethargy.
MODERATE: muscle cramps, weakness, confusion and ataxia.
SEVERE: drowsiness, seizures and coma.
What is the management for hypernatraemia?
Replace the water
What is SIADH?
Too much ADH, causing too much water reabsorption
Low serum Na, high urine osm, high urine Na
NB: SIADH is not a final diagnosis
What are the causes of SIADH?
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Primary brain injury (e.g. meningitis. subarachnoid haemorrhage)
Malignancy (e.g. small-cell lung cancer)
Drugs (e.g. carbamazepine, SSRIs, amitriptyline)
Infectious (e.g. atypical pneumonia, cerebral abscess)
Hypothyroidism
What is the management for SIADH?
Treat the underlying cause
Fluid restrict to 0.5-1L
If ineffective, give demeclocycline/tolvaptan
What is the prolactin axis/pathway?
Hypothalamus -> TRH -> anterior pituitary
Anterior pituitary -> prolactin -> hypothalamus
Hypothalamus -> dopamine -> inhibits anterior pituitary
What are the causes of hyperprolactinaemia?
Pituitary prolactinoma
Hypothyroidism
Metoclopramide/antipsychotics
Pregnancy, breast feeding
What are the clinical features of female hyperprolactinaemia?
Galactorrhoea, amenorrhoea, infertility, loss of libido
Headache, visual field loss
What are the clinical features of female hyperprolactinaemia?
Loss of libido, infertility
Headache, visual field loss
What are the investigations for hyperprolactinaemia?
Prolactin
TFTs
Pituitary MRI
What is the management for hyperprolactinaemia?
DA agonist (bromocriptine/cabergoline) Surgery
What is the thyroid axis/pathway?
Hypothalamus -> TRH -> anterior pituitary
Anterior pituitary -> TSH -> thyroid gland
Thyroid gland -> T3/4
T3/4 negative feedback to Hypothalamus + pituitary
Define hyperthyroidism + give the 2 aetiologies
Excess circulating T4/3 due to:
- increased hormone synthesis (hyperthyroidism)
- increased release of stored hormones (thyroiditis)
What are the signs and symptoms of hyperthyroidism?
Heat intolerance/sweating Palpitations, irregular pulse Irritable, restlessness Weight loss, good appetite Diarrhoea Menstrual irregularity/impotence Tremor, hyperreflexia
What are the signs and symptoms of hypothyroidism?
Cold intolerance Bradycardia Lethary Weight gain Constipation Oligomenorrhoea Dry skin/cold hands Decreased reflexes, c arpel tunnel
What are the types of hyperthyroidism?
Grave’s disease (80%)
De Quervain’s thyroiditis
Toxic multinodular goitre
Adenoma
What is Grave’s disease? Explain the pathophysiology
Autoimmune disease- antibodies to TSH receptors TRAb bind to: receptors on the thyroid behind the eyes the skin Causes inflammation and draws water into the tissue --> Grave’s triad: - exopthalmos - thyroid acropachy - pretibial myxoedema
What is Grave’s triad?
Caused by a TRAb binding:
- Exophthalmos
- Pretibial myxoedema
- Thyroid acropachy= soft tissue swelling of the hands and feet, onycholysis, clubbing and periosteal growth.
Symptoms and signs of De Quervain’s thyroiditis
Post-viral inflammation
3 transient stages:
- hyperthyroidism (virus replicates in thyroid, pushes out T3/4)
- hypothyroidism (as all the T3/4 has been released)
- euthyroid- self-limiting
Painful goitre, fever, ↑ESR
Which 2 cohorts is multinodular goitre more common?
elderly
iodine deficient areas
Define thyroid adenoma
Solitary nodule secreting T3/4
What will you see on a radioisotope scan of Grave’s disease?
Diffuse increased iodine uptake