Electrolyte disorders Flashcards
(71 cards)
1
Q
Acute: cerebral edema, increased risk of seizures or brain herniation - confusion, lethargy, disorientation, fatigue, N/V/watery diarrhea, muscle cramps
Can cause acute renal injury
Chronic: asymptomatic
A
hyponatremia
2
Q
Most common electrolyte disorder due to excess total body water
A
hyponatremia
3
Q
pseudohyponatremia → hypertriglyceridemia, hypergammaglobulinemia (usually a lab error)
A
isotonic hyponatremia
4
Q
hyperglycemia, mannitol infusion
A
hypertonic hyponatremia
5
Q
what are the 3 types of hypotonic hyponatremia?
A
hypovolemic (diuretics, ACE inhibitors, extrarenal or renal volume loss)
isovolemic (SIADH, hypothyroidism)
hypervolemic (edematous states, CHF, nephrotic syndrome, CKD)
6
Q
serum sodium <135
A
hyponatremia
7
Q
steps of hyponatremia for hypovolemia
A
Measure serum osmolality, if low →
Assess volume status → if hypovolemic →
Urine sodium concentration
8
Q
in hypotonic hyponatremia, urine sodium conc <10 is
A
extrarenal loss
→ diarrhea, vomiting, nasogastric suction, diaphoresis, third-spacing, burns, pancreatitis
9
Q
hypotonic hyponatremia >20mm/l UNa=
A
renal loss of volume
→ due to tubular dysfunction - diuretic excess, decreased aldosterone, acute tubular necrosis
10
Q
isovolemic hyponatremia + low urine sodium <20 and low urine osmolality (<100)
A
primary polydipsia or reset osmostat
11
Q
isovolemic hyponatremia + high urine sodium >40 & osmolality >100
A
SIADH
12
Q
maximum correction of hyponatremia is limited to
A
8 mEq/L in 24 hours to prevent overcorrection and osmotic demyelination syndrome
13
Q
ideally sodium correction is
A
4-6/24 hours
14
Q
how do you treat hypovolemic, hypotonic hyponatremia?
A
volume replacement (saline), .9%
15
Q
how do you treat acute symptomatic hyponatremia <48 hours
A
50 mL bolus of 3% saline
16
Q
How do you treat euvolemic hypotonic hyponatremia?
A
water restriction
17
Q
how do you treat hypervolemic hypotonic hyponatremia?
A
volume removal (diuretics), sodium + water restriction
18
Q
how do you treat severe hyponatremia?
A
IV hypertonic bolus
<120 = IV 3% saline
19
Q
how do you treat hypertonic hyponatremia?
A
correct glucose
20
Q
isotonic hyponatremia is generally an
A
error
21
Q
— — — can occur due to rapid overcorrection of hyponatremia
A
Osmotic demyelination syndrome
22
Q
What are RF for osmotic demyelination syndrome?
A
hyponatremia <120, malnutrition, liver disease, alcoholism, concurrent hypokalemia
23
Q
Thirst stimulation, secretion of ADH – confusion, lethargy, disorientation, fatigue, N/V, muscle weakness
Dry mouth or mucous membranes, decreased skin turgor
HOTN
A
hypernatremia
24
Q
Impaired (infants, elderly, debilitated patients), impaired thirst mechanism are at risk for
A
hypernatremia
25
Excess of sodium compared to water, from water loss, or sodium infusion (rarely)
hypernatremia
26
diuretics, GI loss, vomiting, diaphoresis, severe burns (high urine osmolality)
cause ---- hypernatremia
hypovolemic
27
decreased ADH release, decreased ADH response (low urine osmolality)
causes --- hypernatremia
euvolemic
28
cushing syndrome, increased aldosterone release (low urine osmolality) causes --- hypernatremia
hypervolemic
29
>145 – always associated with hyperosmolarity - severe >160
hypernatremia
30
Increased urine osmolality in hypernatremia >600
extrarenal source of water loss
31
Decreased <600 urine osmolality in hypernatremia
renal water loss → obtain volume status (hypo, eu, hyper)
32
<250 urine osmolality in hypernatremia is characteristic of
diabetes insipidus
33
increased Hct, protein, BUN:Cr >20:1, UNa <20
hypovolemic hypernatremia
34
absence of other signs
euvolemic hypernatremia
35
decreased Hct, protein, BUN:Cr in hypernatremia
hypervolemia hypernatremia
36
what should all hypernatremic patients get?
Oral (pure water), D5W IV solution for all patients
>.5mEq/L/hr can result in cerebral edema
37
how do you treat hypovolemic hypernatremia?
isotonic fluids, IV saline, lactated ringers
Hypotonic fluids (½ NS)
38
how do you treat euvolemic hypernatremia?
DI: DDAVP (desmopressin)
non-DI: thiazides
39
how do you treat hypervolemic hypernatremia?
Loop diuretics, can add thiazides to excrete Na
40
Arrhythmias: flattening of T wave <2, sagging of ST segment, U wave formation/T wave depression → can cause PVC, PAC, ventricular/supraventricular arrhythmias, AV blocks, v fib
muscular weakness, fatigue, paralysis, muscle cramps, decreased deep tendon reflexes, paralytic ileus, polyuria and polydipsia
N/V
hypokalemia
41
GI losses: vomiting, nasogastric suction, diarrhea, laxatives, enemas, intestinal fistula
Renal losses: diuretics, renal tubular acidosis I and II, primary and secondary hyperaldosteronism, magnesium deficiency
Shifting: insulin administration, beta 2 agonists, excessive steroids, epinephrine, alkalosis states
K<3.5
<3 = severe
hypokalemia
42
>20 urine potassium means what in hypokalemia?
renal loss of K
→ obtain blood pressure
High BP → aldosterone levels
-----------High = hyperaldosteronism
------------Low = apparent excess of mineralocorticoids
Low BP → magnesium + ABG levels
------------Low magnesium only = hypomagnesemia
--------------Metabolic alkalosis = diuretics
-------------Metabolic acidosis = RTA-1 or RTA-2
43
<20 urine K in hypokalemia means
GI loss of K
→ obtain ABG
Metabolic alkalosis (vomiting/suction)
Metabolic acidosis (diarrhea)
44
how do you treat hypokalemia
K<3 and NO EKG changes: oral potassium, oral KCl, oral KHCO3
K<3 and/or EKG changes: IV KCl
If still low, check magnesium
Low = magnesium supplement
Normal = administer aldosterone antagonist
45
Arrhythmias → tall, peaked T waves, QRS widening, PR interval prolongation, loss of p waves, sine-wave pattern
Muscle weakness, flaccid paralysis, decreased deep tendon reflexes, ileus
N/V/D
hyperkalemia
46
Renal retention
-- Renal failure, hypoaldosterone states, blood transfusion
Redistribution
-- Acidosis, insulin deficiency, beta blocker, digoxin overdose, seizures, rhabdomyolysis, tumor lysis syndrome
Pseudohyperkalemia = lab error (hemolysis from venipuncture)
hyperkalemia
47
GFR:
Low GFR = CKD or AKI
- GFR = hypoaldosteronism → obtain renin + aldosterone levels
Both low = NSAIDs or DM
Aldosterone low = aldosterone insufficiency, ACE/ARB
Both high = K-sparing diuretic, bactrim
RULE OUT SHIFTING
- recent beta blocker or digoxin use, seizure/crush injury, chemo, anemia, acidosis?
hyperkalemia
48
How do you treat hyperkalemia?
K>6
with NO EKG changes
– excrete K from the body with K-binding resin or loop diuretics
WITH EKG changes
Calcium gluconate
Administer insulin +/- D50 and inhaled albuterol and bicarbonate (if acidotic)
refractory/severe AKI/ESRD: hemodialysis
Treat cause – discontinue meds: NSAIDs, ACE/ARBs, k-sparing diuretics, bactrim
49
Numbness and tingling (circumoral, fingers, toes), hyperactive reflexes
Anxiety and depression
May have arrhythmias
Prolonged QT intervals
Increased risk of torsades with low Ca, Mg, K
hypocalcemia
50
MCC: hypoalbuminemia
– decreased PTH or PTH effect (parathyroidectomy or thyroidectomy, hypomagnesemia, pseudohypoparathyroidism)
– decreased vitamin D (malabsorption, decreased sun exposure, CKD)
– calcium sequestration (acute - rhabdo, tumor lysis syndrome, blood transfusion, pancreatitis or chronic - CKD)
hypocalcemia
51
+Chvostek sign
+Trousseau sign
Ca < 8.5 → obtain corrected calcium → obtain PTH level
Low PTH = hypoparathyroidism
No neck history = obtain magnesium
High PTH → obtain phosphate, vitamin D
Both low = vitamin D deficiency
Phosphate high = CKD or pseudohypoparathyroidism → obtain renal function panel
Low GFR = CKD
RULE OUT Ca SEQUESTRATION:
→ seizures, crush injury, AKI and CK, epigastric pain, frequent blood transfusions, chemotherapy
hypocalcemia
52
how do you treat hypocalcemia?
Ca > 7.5 = oral calcium
Ca <7.5 and symptomatic = IV calcium
+ Treat underlying cause:
2ndary hyperparathyroidism, hypoparathyroidism, pseudo: vitamin D
Refractory = thiazides
Hypomagnesemia = magnesium supplement
Hyperphosphatemia in CKD = phosphate binders
53
“Stones, bones, grunts and groans, with psychic overtones”
Nephrolithiasis, nephrocalcinosis, bone pain and aches, osteitis fibrosa cystica → pathologic fractures
Muscle pain and weakness, pancreatitis, PUD, gout, constipation
Depression, fatigue, anorexia, sleep disturbances, anxiety
hypercalcemia
54
Increased PTH – primary and tertiary hyperparathyroidism
Increased vitamin D (granulomatous disease
Increased PTHRP (lung/breast/renal cancers)
Increased bone turnover (MM, metastasis)
hypercalcemia
55
EKG: Shortened QT interval
Ca>10.5 – obtain PTH
-------High = hyperparathyroidism → urine Ca and phosphate
---------------------High calcium = primary hyperparathyroidism
----------------------Both low = FHH
----------------------Both high = tertiary hyperparathyroidism
---------Low → ALP, vitamin D, PTHrP
------------------------High PTHrP = SCC
------------------------High vitamin D = lymphoma or sarcoidosis
-------------------------High ALP = bone metastasis
hypercalcemia
56
hypercalcemia tx
Calcium < 12 + asymptomatic = treat underlying cause
Malignancy: bisphosphonates or denosumab
Hyperparathyroidism: calcimimetics vs parathyroidectomy → surgery
Sarcoidosis or lymphoma: steroids
Calcium > 14 + symptomatic:
IV fluids (.9% saline) + calcitonin + bisphosphonates/denosumab → dialysis
Always treat the underlying cause!
57
Asymptomatic if mild (1-3), symptomatic when <1
Encephalopathy, confusion, seizure, paresthesia
Weakness, myalgias, bone pain, rickets/osteomalacia
Hemolysis, RBC dysfunction, WBC dysfunction, platelet dysfunction
Cardiomyopathy, cardiac arrest
Rhabdomyolysis
hypophosphatemia
58
Redistribution (refeeding syndrome/insulin secretion, acute respiratory alkalosis, hungry bone syndrome)
Decreased GI absorption – inadequate intake, inhibition of absorption, steatorrhea/chronic diarrhea, vitamin D deficiency, TPN w/o adequate phosphate
Increased urinary excretion - primary/secondary hyperparathyroidism, hypophosphatemic rickets, Fanconi syndrome, drugs (acetazolamide, tenofovir, iron, chemo)
hypophosphatemia
59
Detailed history
Measure urine phosphate:
Low = inadequate intake or absorption
High → measure PTH
------------Normal → measure vitamin D and calcium
----------------------FGF23 mediated
----------------------High = intrinsic renal defect
---------------High = hyperparathyroidism
hypophosphatemia
60
hypophosphatemia tx
Mild = oral supplementation, K+ phosphate tablets, milk, neutra-phos capsules
Severe = <1 → IV supplementation
61
Itself is asymptomatic - correlates with underlying cause
hyperphosphatemia
62
MCC: renal insufficiency, bisphosphonates, hypoparathyroidism, vitamin D intoxication, increased phosphate administration, rhabdomyolysis, tumor lysis syndrome, acidosis
hyperphosphatemia
63
how do you treat hyperphosphatemia?
Treat underlying cause
Symptomatic hypocalcemia w/ EKG changes: calcium gluconate
Impaired kidney function: hemodialysis
Chronic hypophosphatemia: decreased dietary intake, oral phosphate binders
64
Usually asymptomatic, marked neuromuscular and CNS hyperirritability (muscle twitching, weakness, tremors, increased tendon reflexes - generally first sign, seizures, AMS)
Hypocalcemia and hypokalemia
EKG: prolonged QT interval, T wave flattening → torsades de pointes ultimately
Trousseau and Chvostek signs also seen here
hypomagnesemia
65
GI causes: malabsorption, steatorrhea states (MC), vomiting, diarrhea, laxative use, PPIs, fistula
TPN w/o supplementation, alcoholism, renal causes (diuretics, amphotericin B, cisplatin, renal transplantation, hypercalcemia, gitelman syndrome)
Post-parathyroidectomy, alkalosis, thyrotoxicosis, lactation, refeeding syndrome, pregnancy
hypomagnesemia
66
Check FeMg
<2-2.5% → GI loss (Diarrhea, PPI use, malabsorption)
>2-2.5% → renal loss → check urinary calcium level
------------------>250 = proximal and TAL effect (loop diuretics, hypercalcemia-PTH effect, familial hypomagnesemia with hypercalciuria and nephrocalcinosis, meds)
--------------------<150 = distal nephron, Gitelman’s syndrome, thiazides, cetuximab and other EGFR ab, genetic defects
hypomagnesemia
67
hypomagnesemia tx
Mild: oral magnesium
Severe/symptomatic: IV magnesium sulfate
68
Nausea, weakness, facial paresthesias (5-7) → loss of tendon reflexes → somnolence, coma, HOTN, bradycardia, EKG abnormalities similar to hyperkalemia (7-12) → muscular paralysis, respiratory failure, cardiac arrest
hypermagnesemia
69
MCC: CKD
Early stage burns, trauma, surgical stress, excessive intake of magnesium-containing laxatives, adrenal insufficiency, rhabdomyolysis, familial hypocalciuria hypercalcemia, iatrogenic
hypermagnesemia
70
Elevated serum magnesium is diagnostic
CKD: BUN, Cr, K, phosphate, uric acid levels elevated + low GFR
hypermagnesemia
71
hypermagnesemia tx
Stop magnesium intake – IV calcium gluconate + saline + furosemide + dialysis + intubation
