Electrolyte imbalances and DI Flashcards
where are ADH an oxytocin made
posterior pituitary gland and supraoptic nucleus
adh receptors?
v1a- vasculature
v2- renal collecting tubes- reabsorption of water
v1b- pituitary
ADH release is controlled by
osmoreceptors in hypothalamus - day to day
baroreceptors in brainstem and great vessels
what is osmolality
mOsmol/kg
what factors can affect osmolality
number of particles
concentration of ions
presence of solutes
disease associated with the posterior pituitary
1-lack of vasopressin = AVP deficiency
2-resistance to action of vasopressin= avp resistance
3-inappropiate ADH release
what happens with high adh levels
conc urine
high urine osmolality
what does avp resistance and deficiency cause
polyuria
polydipsia
no glycosuria
how to diagnose diabetes insipidus
measure urine volume
check renal function and serum calcium
Difference between cranial and nephrogenic DI
Cranial- decrease in production of ADH
Nephrogenic- impaired response to adh
causes of AVP deficiency
acquired- idiopathic, tumours , trauma
primary- autosomal dominant
common cause of AVP resistance
lithium
management of avp deficiency
treat underlying condition
desmopressin- high activity at V2 receptor
define hyponatraemia
serum sodium < 135 mmol/l
severe <125 mmol/l
normal serum sodium levels
135- 144mmol
moderate symptoms of hyponatraemia
Headache
* Irritability
* Nausea / vomiting
* Mental slowing
* Unstable gait / falls
* Confusion / delirium
* Disorientation
severe symptoms of hyponatraemis
stupor/coma
convulsions
resp arrest
what is hypocalcaemia
low calcium levels in blood serum
Common causes of hypocalcaemia
Hypoparathyroidism
Vit d deficiency
Kidney failure
corrected calcium equation?
total serum ca + 0.02 x (40-serum albumin)
presentation of hypocalcaemia
Spasm
Parasthesia
Anxious
Seizures
Muscle tone increase
Orientation impaired
Dermatitis
Impetigo
Cardiomyopathy
investigation of hypocalcaemia
levels of PTH, VIT D
serum calcium levels
ecg- prolonged QT interval
treatment of hypocalcaemia
Acute- IV calcium gluconate
complications of hypocalcaemia
seizure
cardiac arrest
what is hypercalcaemia
decrease PTH
increase ca2+
Causes of hypercalcaemia
Primary hyperparathyroidism
Malignancy
Sarcoidosis
Symptoms of hypercalcaemia
abormal bone remodelling
kidney stones
abdo pain
lethargy,depression
investigations for hypercalcaemia
-fasting serum and phosphate samples
serum pth and ca2+
ultrasiund if investigations point to primary hyperparathyroidism
treatment for hypercalcaemia
- rehydration with saline
-rehydration with bisphosphonates
-furosemide
define hyperkalaemia
serum potassium <3.5mmol/l
cause of hypokalaemia
decrease K intake
increase of K into cells
increase in K excretion
presentation of hypokalaemia
muscle weakness
hyporeflexia
cramps
what would an ecg show for hypokalaemia
Small or inverted t waves
prominent U waves
long PR interval
depressed ST segments
investigations for hypokalemia
metabolic panel
ecg
urine electrolytes
treatment for hypokalaemia
mild- ORAL replacement -
SEVERE- IV replacement 40mml
complications of CVD
chronic heart failure , Acute MI
long QT syndrome
define hyperkalaemia
serum potassium >5.5
causes of hyperkalaemia
increase intake
increased production
shift from intracellular to extracellular
clinical presentation of hyperkalaemia
neuromuscular transmission
muscle weakness and paralysis
chest pain
Hyperreflexia
what would an ecg show for a patient with hyperkalaemia
Tall tented t waves
small P waves
Wide QRS complex
Ventricular fibrilations
treatment of hyperkalemia
If ECG changes- stabilise cardiac membrane by IV calcium gluconate
if no changes in ecg- comined insulin/ dextrose with nebulised salbutamol
what is carcinoid syndrome
occurs due to the release of serotonin from a carcinoid tumour
most common cause of carcinoid syndrome
small intestine malignancy
presentation of carcinoid syndrome
flushing, diarrohoea, abdo cramos , bronchospasm, fibrosis
1st line test for carcinoid syndrome
urinary 5-hydroxyindoleacetic acid test
what electrolyte disturbance would make you consider SIADH
hyponatraemis
Three types of cancers that cause SIADH
small cell carcinoma
Prostate cancer
Cancer of thymus
Role of pth
Increase bone remodelling and turnover
Pth increases the amount of calcium absorbed in the kidney which means less excreted in kidney
Increases absorption of ca in thr gut
