Electrolytes Flashcards
HypoK alkalosis causes?
If high BP: - high aldo low renin: Conn's, GRA - low aldo low renin: Liddle, AME, Licorice If normal BP: - If FECl < 0.5%: extrarenal hypoVol - If FECl > 0.5%: Bartter / gitelman
HyperK acidosis causes?
if high BP: PHA2 if normal BP: - high aldo high renin: PHA1 - low aldo high renin: adrenal insufficiency, aldo biosynthesis deficiency - low aldo low renin: DM, CNI, NSAID
bartter types and features?
BS1: NKCC; hypercalciuria, pre-natal onset
BS2: ROMK; hypercalciuria, prenatal onset
BS3: ClCKNB; hypoMg, first decade
BS4: Barttin; SNHL
BS5: CaSR overactivation cause FHH
All: reduce Cl resorption -> TGR reduce -> increase PGE2 -> increase RAAS
bartter MOI?
AR
bartter Tx?
NSAID (indomethacine 1-3mg/kg/d)
KCl
spirolactone but watch out for hypoVol
gitelman MOI?
AR
bartter symptoms?
hypoK, alkalosis, hypoVol, polyuria, hypercalciuria and nephrocalcinosis if BS1-2
gitelman cause?
SLC12A3 inactivation mutation -> loss of NCCT function
gitelman features?
hypoK, alkalosis, hypoMg, polyuria, chondrocalcinosis, sclerochoroidal calcification
gitelman ddx?
BS3, HNF1B, EAST, Sjogren, thiazide use
gitelman Tx?
KCl and Mg supp, spirolactone if severe
features of EAST?
Epilepsy, Ataxia, SNHL, tubulopathy (same as gitelman)
Liddle MOI?
AD
Liddle cause?
mutation of overactive ENaC
Liddle ddx?
GRA, AME, Licorice
AME cause?
11 beta hydroxyvitamin dehydrogenase deficiency
reduce cortisol conversion to cortisone thus activate MR
AME MOI?
AR
AME feature?
hypoK alkalosis high BP low aldo low renin
AME Ix?
increase tetrahydrocortisol (THF) or allo-THF to tetrahydrocortisone (THE) level genetic test
AME Tx?
spirolactone / amiloride
GRA MOI?
AD
GRA feature?
Early HT, hypoK, alkalosis, high BP, low renin, high aldo
prone to ICH
GRA cause?
CYP11B1 (11beta hydroxylase for aldo) promoter fuse with CYP11B2 (aldo synthatase) on Ch8 to cause ACTH induced Aldo production
GRA Ix?
increased hybrid steroid (18 hydroxycortisol and 18 oxocortisol)
GRA Tx?
Pred 2.5 - 5mg daily +/- spirolactone / amiloride
PHA1 MOI?
AR or AD
PHA1 cause?
ENaC defect, acquired form from obstructive uropathy +/- pyelonephritis
PHA1 features?
hyperK, acidosis, normal BP, high renin high aldo, miliary rash from high Na sweet, CF like high salt lung secretion
PHA1 Tx?
NS IVF, NaCl and NaHCO3 replacement, Na resin
PHA2 MOI?
AD
PHA2 cause?
WNK4 inactivating mutation, disinhibit NCCT and ROMK function
WNK1 activating mutation, inhibit WNK4
acquired form by CNI
PHA2 features?
hyperK from birth or later, NAGMA, low renin and aldo
PHA2 Tx?
Thiazide
NDI MOI?
XR, female carrier variable severity
rarely AR / AD
NDI cause?
CKD hypoK, hyperCa SCD malnutrition demeclocycline, Li use (block by amiloride) pregnancy AVPR2 mutation AR / AD AQP2 final effector protein
NDI features?
first week of month polyuria, FTT, vomiting
dystrophic calcification in BG
ADHD due to drinking?
NDI Ix?
low urine osmo with hyperNa
DDAVP test (limit intake Vol to UO to avoid rapid hypoNa), 0.3mcg/kg IV observe 2 hrs
Uosmo > 800 mOsm/kg normal, remains < 200 diagnostic
infant may < 800 but should > 300
AR / AD still has AVPR2 thus will have BP drop (vasodilatation) and release vWF
NDI ddx?
Central DI / habitual polydipsia (ddx by DDAVP normal response)
secondary NDI: Bartter (with polyhydramnios), AME (HT)
NDI Tx?
minimize osmotic load by low protein and caloric intake
thiazide (HCT 1-2mg/kgQ12)reduce salt reabsorption -> mild hypoVol -> increase fluid reabsorpton in PT
+/- amiloride to control hypoK
COXi reduce UO
NSIAD cause?
gain of function mutation of AVPR2
NSIAD MOI?
XD
NSIAD features?
Uosmo > 100 in hypoNa hypoosmo, but has low vasopressin (vs SIADH)
NSIAD Tx?
FR, increase osmotic load (e.g. Urea)
AVPR2 blocker not useful due to no vasopressin excess
pseudohypoNa cause?
solid phase of serum increase by lipid or protein e.g. TG, paraprotein
-> serum osmo normal
direct ion selective potentiometry can measure true aqueous Na activity
How to calculate water excess / deficit
0.6 x body weight x (1- Na/140) or (Na/140 - 1)
hypoNa hypoVol causes?
Urine Na > 20 renal loss:
diuretics, MR deficiency, salt losing nephropathy (in GFR < 15, pRTA), Bicarbonaturia with RTA, ketonuria, osmotic diuresis, CSW (BNP increase urine Vol, ddx NSAID: hypoVol)
Urine Na < 20 extra renal loss:
vomitng, diarrhea, third space loss (peritonitis, pancreatitis, ileus in lumen)
hypoNa euvolemic cause?
addisonism, hypothyroidism, stress, drugs (desmopressin, carbamazepine . SSRI (enhance AVP release), Haldol, MDMA, IVIG) , SIADH
hypoNa hypervolemia cause?
urine Na > 20: AKI
urine Na < 20: cirrhosis, NS, CHF
Causes of SIADH?
CA: brochogenic tumor Lung: pneumonia CNS: meningoencephalitis, HI Others: HIV idiopathic
SIADH dx criteria?
Sosmo < 270 Uosmo > 100 euvolemia high urine Na no adrenal, thyroid, pituitary, renal insufficiency and diuretics use
Tx of hypoNa?
acute symptomatic <48hr: - 3% NaCl 1-2 ml/kg over 60min +/- lasix chronic symptomatic: - 3% NaCl 1-2ml/kg/h if seizure +/- lasix - FR aim correct < 8mmolLL chronic asymptomatic: - FR - demeclocycline 300 - 600bd (S/E neurotoxic, nephrotoxic, photosensitive, polyuria) - Urea 15-60g daily - NaCl 2-3g +/- lasix - V2RA
How to estimate Na correction rate?
Adrogue formula:
Change in serum Na = ((infusate Na + infusate K) - serum Na) / TBW + 1
but did not account for renal and extrarenal loss of free water
may give DDAVP to prevent hypotonic urine
NS Na amount?
154 mmol/L
Tx of CHF induced hypoNa?
salt and FR
ACEI, loop diuretics
V2RA
hyperNa hypoVol causes?
urine NA > 20 renal loss: diuretics, post obstruction, renal disease
urine Na < 20 extra renal:
GI, burn, fistula
hyperNa euvolemic cause?
renal loss: DI, hypodipsia
extrarenal loss: insensible loss
hyperNa hyperVol cause?
Na gain:
primary hyperaldo
cushing
hypertonic dialysis, NaCl, hypertonic NaHCO3
DI dx?
water deprivation test
FR till 3-5% BW loss or 3x hour urine osmo similar
DDAVP given 5 unit SC and measure urine osmo after 60min
normal Uosmo > 800 complete central DI: Uosmo < 300 partial central DI: 300 - 800 NDI: <300 primary polydipsia > 500
after DDAVP NDI no change, CDI increase substantially
Diff primary polydipsia and DI?
serum osmo < 270 polydipsia
serum osmo > 295 DI
CDI causes?
Congential: AR / AD (1st year of life) Acquired post traumatic metastatic CA breast, NP, histocytosis, TB, aneurysm, meningioencephalitis Drugs GBS
CDI Tx?
DDAVP 10-20mcg IN Q12-24hr
or PO 0.1-0.8mg Q12hr
+/- chlorpropamide, clofibrate, carbamazepine to potentiate
pseudohypoK cause?
large number of cell takes up K (acute leukemia)
Px by cooling and rapid separate plasma
hypoK workflow?
high aldo, insulin, theophylline, hyperT, adrenergic agent use
-> redistribution
Urine K < 20mmol/24hr -ve: GI loss
Urine K > 20mmol/24hr:
- acidotic: RTA1/2, acetozolamide, DKA osmostic diuresis,
- alkalotic:
BP high - Conn’s, Cushing, AME (low renin / aldo), liddle (low renin / aldo), GRA (low renin, high aldo)
BP low - diuretics, hypovolemia, bartter / gitelman,
Liddle Dx?
genetic test
liddle Tx?
amiloride
hyperK workup?
pseudohyperK due to cell lysis, dx by diff K in serum (clotted) and plasma (no clotting)
trancellular shift: BB, insulin insufficiency
reduced GFR: CKD
normal GFR:
- hyporeninemic hypoaldo: DM, Drug: NSAID, BB, CNI
- hypereninemic hypoaldo: adrenal insufficiency, ACEI / ARB, heparin, ketoconazole
- hypereninemic hyperaldo: drug spirloactone, amiloride, septrin, pentamidine, PH1, PH2
TTKG calculation?
Uk / Sk // Uosm / Sosm
< 7 in hyperK suggest renal K retention
hyperCa causes?
high PTH: adenoma, hyperplasia, MEN1 / 2A, FHH (AD, inactivating mutation in CaSR)
malignancy: PTHrP, bone metastasis, hemato
granulomatous: TB, sarcoidosis
Vit D intoxication
Endocrine: hyperthyroid, acromegaly, pheochrommocytoma
pseudohyperparathryoid (with short limb, metaphysal chrondrodysplasia, due to PTH1B activating mutation
FHH dx?
FECa: Uca / Sca // Ucr / Scr < 1%
hyperCa sym?
fatigue, weakness constipation PUD, pancreatitis polyuria (NDI) renal stone Neuro: headache conjunctivitis, band keratopathy short QT
hyperCa Tx?
NS +/- Lasix
bisphosphonate (pamidronate 15-90mg IV, Zolandronic acid 4mg IV
Calcitonin IV . IN
Denosumab (RANKL Ab)
steroid if VitD / TB / scarcoidosis related
if malignant hyperCa: PG antagoinst (NSAID)
Propanolol if hyperthryoid
cinacalcet / VitD / surgery if 1st hyperPTH
Hungry bone syndrome biochem features?
hypoPO4 hypoCa hypoMg hyperK
hungry bone Tx?
Ca: 2-4g oral, IV if symptomatic or < 1.9
oral calcitriol 4mcg/day
avoid replacing PO4 unless extremely low < 0.32
hungry bone Px?
off paricalcitrol and cinacalcet and PO4 binder
Q8H CaPO4 Q8H checking
start caltrate 1.5g tds, Rocaltrol 0.5mcg bd
hypoCa sym?
weakness, confusion, paranoia, chvostek, trousseau, parasthesia of lips and extremities, tetany, seizure
chronic hypoCa cataract, brittle nail, transverse grooves, dry skin, absent axillary and pubic hair
hypoCa causes?
false hypocalcemia (Adj Ca = Ca + (40 - Alb) x 0.025)
low PTH:
- post parathyroidectomy (hungry bone) / neck dissection / radiation
- autoimmune polyglandular syndrome
- infiltration of parathyroid: granulomatous, metastasis, FE overload
- HIV
- hypoMg
high PTH:
- Vit D deficiency (liver, GI, CKD)
- PTH resistance: pseudohypoparathyroidism
- loss of Ca from circulation: hyperPO4, pancreatitis, tumor lysis, acute illness
Drug: bone resorption inhibitors (bisphosphonate, calcitonin, denosumab), cinacalcet, foscarnet (complex with Ca), phenytoin (conversion of Vit D to inactive meatbolite, FE poisoning
HypoMg
hypoCa Ix?
PTH low:
- low Mg: hypoMg
- normal Mg: hypoPTH
PTH high:
- PO4 high: CKD, PTH resistance
- PO4 low / N: Vit D deficiency
MEN1 / 2a / 2b features?
MEN1: pituitary adenoma, parathyroid hyperplasia, pancreatic tumor
MEN2a: parathyroid hyperplasia, medullary CA thyroid, phenochromocytoma
MEN2B: mucosal neuroma, marfanoid, medullary CA thyroid, pheochromocytoma
hypoCa Tx?
IV / PO Ca, Vit D
thiazide if hypoPTH
hyperPO4 causes?
redued renal excretion:
- CKD: high PTH and FGF23 to excrete PO4
- hypoPTH
- pseudohypoparathyroid
- Drug: bisphosphonate
- acromegaly (increase tubular resorption stimulatied by GH and IGF1
increase endogenous supply:
- cell lysis (rhabdo, TLS)
- respi alkalosis
lactic acidosis
increase exogenous supply:
- PO4 soda
- Vit D
hypoPO4 causes?
increase urine loss:
- hyperPTH
- Vit D deficiency
- diuretics
- steroid use
- fanconi, dRTA
- alcoholism
- post renal transplant (high FGF23)
decrease GI absorption
- Vit D deficiency
- malabsorption
intracellular transfer
- hungry bone
- respi alkalosis
- TPN, refeeding
inherited
- X linked hypoPO4 ricket
PO4 reference range?
1-1.5mmol/L
hypoPO4 sym?
encephalopathy, hemolysis, thrombocytopenia, respi failure, rhabdomyolysis, cardiomyopathy
hypoPO4 Tx?
PO / IV replacement
hypoMg causes?
GI disease:
- malabsorption, SB resection
urinary losses:
polyuric state, acidosis, hyperCA, primary aldosteroid, hyperthyroid, gitelman
Drug cause:
- aminoglycoside, amphotericin, cisplatin, cyclosporin, pentamidine, thiazide, PPI
Anion Gap calculation?
Na - Cl - HCO3, cut off 12 +/- 2
albumin adjust: adjusted AG = AG + (40 - alb) x 0.25
HAGMA causes?
ketoacid: DKA / AKA
lactic acidosis: L/D
Substance: methanol, ethylene glycol, panadol, salicylate
NAGMA causes?
GI cause: diarrhea, ureterosigmoidostomy
Renal cause: RTA1/2/4, CKD
Endocrine: hypoaldo
Drug: NSAID, acetazolamide
UAG calculation?
UNa + UK - UCl
+: inability to excrete NH4
-: appropriate excretion
if unmeasured ion present e.g. DKA, hippuric acid, bicarbonate
UOG: measured osmo - (2 x (UNa + UK) + Urea + Uglu)
if > 100 mOsmo/kg suggest normal NH4 excretion
Diff RTA
hyperK: RTA 4
- urine pH < 5.5 low aldo secretion
- urine pH > 5.5: CCD abnormality
RTA2: fanconi (euglycemic glucosuria, hypoPO4, hypoUrate, mild proteinuria), urine pH > 5.5
causes of RTA2
MM, LCDD hyperPTH Drug: getamycin, TDF (tenovovir dixoproxil fumarate, avoid by tenovovir alafenamide fumarate) Lead, cadmium, mercury TIN: rejection, MCKD
RTA1 causes?
Autoimmune: Sjogren, PBC, SLE
Drug: amphoB, toluene
Nephrocalcinosis: hyperPTH, VitD
TIN: obstructive uropathy, transplant
lactic acidosis cause?
type A: hypoperfusion / hypoxia - shock, CO poisoning, anaemia type B: other - Drug: Metformin, salicyclate, ethylene glycol, methanol, propylene glycol, linezolid, propofol, NRTI, isonizid - thiamine deficiency - systemic: liver failure, malignancy - hereditary (G6P)
L vs D lactate?
D: SB resection / steatorrhea, causing bacterial overgrowth
Tx by low carbo diet and antimicrobial
AKA diff DKA?
high B hydroxybutyrate to acetoacetate ratio
AKA Tx?
glucose infusion
Ethylene glycol and methanol sym?
EG:
0-12: confusion
12-24hr: APO
24-36hr: frank pain, AKI, CA oxalate crystal
methanol:
0-12 asymptomatic
24-36: pancreatitis, retinal edema
48: putamen and white matter hemorrhage
ethylene glycol / methanol Tx?
fomepizole 15mg/kg IV loading then 10mg /kg Q12H then 15mg/kg Q12H after 48hr
IV ethanol 5/10% solution
HD
HCO3
OG calculation?
measured osmo - 2x Na + urea + glucose + (1.25 x Ethanol)
high than 10 indicates toxic alcohol
metabolic alkalosis workup?
Chloride resistance: UCl > 30: aldo excess or aldosteroism, tubular problem (bartter, gitelman) check renin / aldo UCl < 10: renal loss: diuretics GI loss: vomiting
Winter formula
1.5 x HCO3 + 8 +/- 2
mmHg to kPa: divided by 7.5
delta delta ratio
AG - 12 / 24 - HCO3
1 - 2: HAGMA
> 2: Mixed HAGMA + metabolic alkalosis: vomiting, diuretics
< 1: Mixed HAGMA + NAGMA: diarrhea
