Metabolic Medicine Flashcards
What are some causes of hyperkalemia?
acute kidney injury
drugs*: potassium sparing diuretics, ACE inhibitors, angiotensin 2 receptor blockers, spironolactone, ciclosporin, heparin**
metabolic acidosis
Addison’s disease
rhabdomyolysis
massive blood transfusion
What would you expect the K+ to be in DKA?
Low due to total body loss
When is hyponatraemia considered chronic?
> 48 hours
or
duration of symptoms are not known
What is the serious potential consequence of osmotic demyelination?
Locked in syndrome
How is Hyponatremia treated?
Mild cases/ usually associated with edematous fluid:
- fluid restriction
- diuretics - furosemide
Hypovolaemic
- 0.9% saline
Severe:
- hypertonic saline
SIADH:
- fluid restriction
- Saline
- Tolvaptan - ADH receptor antagonist
when should calcium gluconate be given?
K+ >6.5
or ECG changes
What is the maximum rate K+Cl can be infused at?
20mmol/Hour
or
Max concentration of: 40mmol/L
List come causes of SIADH:
Small cell lung cancer
Subarachnoid bleed
Mycoplasma pneumonia
Meningitis
Drugs
- carbamazepine
- SSRI
Surgery
What are the symptoms of SIADH?
lethargy
headaches
dizziness
Postural Hypotension
ataxia
confusion
Seizures
Coma
How is hypernatremia investigated and treated?
Fluid status
Serum osmolality
Urine Na2+/ osmolarity
Treatment:
Acute - Dextrose 5%
Chronic: slow adjustment <10mmol daily
- fluids
Dehydration
- 0.9% saline
What are some etiologies for diabetes insipidus?
Cranial:
- x-linked condition
- Idiopathic (typically autoimmune)
- Head injury
- Craniopharyngioma
- Infection
- surgical
Nephrogenic:
- Drugs - lithium
- Receptor defect
- Hypercalcaemia
What is the diagnostic investigation into Diabetes insipidus?
Water deprivation test / Desmopressin Stimulation test
Urine osmolarity measured
If someone had hypernatremia and underwent investigations into diabetes insipidus, and their results turned out to be primary polydipsia what would you expect the urine osmolality results to be?
Pre- desmopressin
- high osmolality (trying to reabsorb water)
Post desmopressin
- High osmolality (still trying to reabsorb water)
What things may give an artificially high K+ readying?
Contamination of K from EDTA tubes
- U&Es should be done first
Thrombocythemia
- K+ leaks out as the platelets try to clot
Delayed analysis
- K+ leaks out as cell decay
Poor venipuncture
How should severe hyponatremia be treated?
slow infusion of IV saline if >48 hours
Infusion of IV saline if <48 hours
What is the effect of hypokalemia on the heart?
Increased ventricular ectopics leadign to:
- VT
- VF
- Torsade de point
- decreases repolarisation inducing Early- after depolarisations
- increase ventricular rate
U waves are seen
What is considered severe hypokalemia?
<2.5mmol
What drug can hypokalemia induce severe toxicity in?
Digoxin
What “malignancy” investigations should be done into hypercalcemia?
FBC
- Anaemia
Imaging
- Bone scan
- CXR
- Neck US
Electrophoresis
- myeloma
Alkaline Phosphatase
- Bone mets
What is the management for severe Hypercalcaemia and what daily monitoring should be done?
Dehydration Furosemide Bisphosphonates - Zoledronic acid \+/- Steroids (myeloma, sarcoidosis)
Daily Monitoring:
- Ca2+
- U&Es
- Mg2+
Which drugs cause SIADH?
Cant Concentrate Serum Sodium
- carbamazepine
- cyclophosphamide
- SSRIs
What is first line treatment for hypercalcaemia?
IV fluid
In dehydration what would you expect the haematocrit and serum haemoglobin to be?
Slightly raised
- relative polycythemia
Which commonly used antithrombotic drug can cause a rise in K+?
Heparin
List some causes of Hypocalcemia?
Hypoparathyroidism
- autoimmune/ thyroidectomy
CKD
Low vitamin D
Hypomagnesemia
Acute pancreatitis
Celiac disease
- unable to absorb
Crohn’s
Tumour lysis syndrome
What are two classical signs seen in hypocalcemia:
Trousseau’s sign
- inflating cuff causing hand to cramp
Chvostek’s sign
- taping facial nerve triggers facial twitch
What is the management for hypocalcemia?
Mild:
- calcium supplements
- Mg2+
CKD:
- phosphate binders
- Mg2+ correction
- Vitamin D supplementation
Severe:
- Calcium gluconate
- Mg correction
What are some common causes to hypomagnesemia?
Deficiency in diet
Diuretic use
Reduced G.I absorption
Pancreatitis
How is hypomagnesemia treated?
Mg2+ infusion with glucose
What do the bloods show in primary hyperparathyroidism?
High PTH
High Ca2+
Low PO4-
What do the bloods show in secondary hyperparathyroidism?
High PTH
Low/ normal Ca2+
High PO4-
What are the causes of hypokalemia?
Transcellular shit:
- Beta agonists (salbutamol)
- Alkalosis
G.I loses
- Diarrhea
Mineralocorticoid stimulation
- Conn’s syndrome
- Cushing’s disease
Drugs:
- Loop diuretics
For mild hypokalemia (>2.5) what drug can be given?
Sando K
What are the signs and symptoms of hyperkalemia?
lethargy Mental slowness Muscle weakness Palpitation Chest pain
What is the dose of calcium gluconate given in hyperkalemia?
10% in 10ml over 10mins
What medications can push K+ up?
ACE inhbiitors
ARBs
Aldosteronism antagonists
What things need to be excluded for SIADH?
Abnormal Cortisol
TFTs
What are the common medications that cause Hyponatremia?
Omprzole
SSRIs
Carbamazepine
What affect can calcium have in the G.I other than constipation?
Calcium can promote gastrin release causing peptic ulcers
What changes radiologically are seen with hyperparathyroidism?
Subperiosteal bone resorption
Pepperpot skull
Acroosteolysis
- reabsorption of the distal phalanges
What is the effective of hypercalamia on blood pressure?
Increased the diastolic pressure due to arterial contraction
What are the investigations into hyperparathyroidism?
Bloods:
- corrected calcium
- PTH
Orifices:
- Calcium
X-rays:
Head and bones
- subperiosteal erosion
- Pepper pot skull
Special tests:
- Technetium Sestamibi radionuclide scan
- localisation of adenoma
What are the typical lab findings for secondary hyperparathyroidism?
Normal to Low Calcium
High Phosphate
*phosphate is high because the kidney is unable to effectively secrete the phosphate away.
Ca2+ is normal to low because it was low in first place and this is correcting it, plus large amounts of PO4- inhibit its reabsorption
What are the indications for surgery in primary hyperthyroidism?
<50 years Calcium >3 Severe Neurological symptoms Nephrolithiasis Reduced Bone density
What is one of the most common causes of dilutional hyponatremia?
Post operative
- excessive fluid resuscitation
What is the maximum the fluid osmolality can be changed?
10-12mmol/L in 24 hours
2mmol/L an hour
Which drug is a ADH receptor antagonist?
Tolvaptan
What deposits of calcium may be seen?
Chondrocalcinosis
Corneal calcification
What is the major complication following parathyroid surgery, and what can be done to minimise it and how is it followed up?
Hypocalcaemia is the major complication
Monitored before and after the surgery.
those at high risk can be given supplemental calcium dn vitamin D before hand.
What are the signs and symptoms of hypokalamia?
Weakness
Intestinal Ileus
Cramps
Tetany
What must be ruled out in order for there to be SIADH, and why?
Need to rule out hypothalamic-pituitary axis defects.
- remember that adrenal insufficiency can give a similar picture with the severe hyponatremia
With results of an extremely high PTH, with moderately raised calcium - what type of PTH is this?
Teitrary
It causes massively raised PTH level
