Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

nephrology > electrolyte imbalances > Flashcards

electrolyte imbalances Flashcards

(51 cards)

Start Studying
1
Q

How do we maintain normal plasma osmolality: intake

A
  • Regulated by Osmoreceptors in Anterolateral Hypothalamus that detect Tonicity
  • Thirst response activated when Osmolality = 295 mOsm -> happens LATE
  • if pt is thristy at ER: really dehydrated
  • normal: 275-290
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How do we maintain normal plasma osmolality: excretion

A
  • Regulated by Osmoreceptors that detect ADH & Tonicity
  • ADH is released when Osmolality = 280-290 mOsm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

renal causes of hypovolemia vs extra-renal

A

renal:
- Diuretics
- Osmotic Diuresis
- Hypoaldosteronism
- Salt-wasting
- DI

extrarenal:
- GI loss
- skin loss: sweating
- respiratory
- hemorrhage: pure blood loss = water loss

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

osmolarity vs tonicity

A

Osmolarity: Objective, quantitative value that determines concentration
- what you measure in a test tube

Tonicity: Subjective, comparative value that assess movement of substance between two solutions separated by membrane
- is in relation between membrane and permeability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

hypovolemia labs: urine Na+, osmolality, sp gravity

A

Urine Sodium:
- < 20 mM/L
- Due to increased sodium reabsorption to retain body fluid volumes

Urine Osmolality:
- >450 mOsm
- Due to decreased urine output

Urine Specific Gravity:
- 1.015
- Higher due to decreased urine output

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Hypovolemia: the ECF is ________. list 3 categories/causes of hypovolemia

A

NORMAL OR EXPANDED ECF

Decreased CO: reduces circulating blood volume
- sepsis

Redistribution:
- Hypoalbuminemia: Decreased oncotic pressure = ↓ Intravascular Volume
- Capillary Leakage: Fluid seeping into interstitial spaces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

hypovolemia labs: BUN:Cr

A

BUN: Cr
- normal: 10:1
- prerenal azotemia (decreased renal perfusion) + GI conditions: >20:1
- dehydration: 20:1

Urinary values:
- < 20
- >

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

hypovolemia tx:

A
  • Based on severity
  • Mild: Slow oral rehydration
  • IV fluids: based on electrolyte abnormality OR cause of hypovolemia (ie. active GI bleed)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Types of IV Fluids

A

Normal Saline: ECF replacement due to low osmotic pressure
- mostly distributed to INTERSTITIAL -> could cause third space

D5W: Maintenance fluid that is distributed throughout ALL compartments due to dextrose passing into all compartments

Fresh Frozen Plasma: Colloid that primarily stays intravascular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Hyponatremia: what are the sx dependent on

A

often associated with hypovolemia

dependent on :
- RATE of decrease: faster decline = more sx
- plasma level of sodium: really low Na+ = more sx

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Hyponatremia: cycle of events in the brain

A

hypotonic state -> water gain causes excess water to move into the brain cells
- swelling: headache, nausea/vomit

rapid adaptation: brain cells respond by active transport to push electrolytes out of cells so water follows

slow adaption: loss of organic osmolytes

too rapid correction of hyponatremia = OSMOTIC DEMYELINATION
- damage to myelin; life threatening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Hyponatremia sx

A

mostly neurologic sx

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Dx hyponatremia

A

Definition: plasma osmolality under 135
- normal: 135-145

other labs:
- Urine Osmolality
[Na+] Urine and [K+] Urine:
- Potassium is wanted to since both Na+ and K+ influence the body’s tonicity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

hyponatremia with high plasma osmolality DDx

A
  • Hyperglycemia: uncontrolled DM
  • Mannitol

usually caused by the presence of other osmotically active substances in the blood that can draw water out of cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

hyponatremia with normal plasma osmolality DDx

A

occur in cases where there is an increase in other plasma components such as protein and lipids - > these conditions can affect the measurement of sodium

  • hyperproteinemia: multiple myeloma; neoplasms
  • hyperlipidemia
  • after bladder irrigation process
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

hyponatremia with low plasma osmolality DDx first steps

A

1) check urine osmolality: see if its excess water intake and assess kidney function

Urine osmolality < 100 mOsm:
- primary polydipsia
- osmostat error
- suggests that the kidneys are responding appropriately to the hyponatremia by excreting dilute urine

Urine osmolalilty > 100 mOsm:
- implies that the kidneys are still concentrating urine -> indicates body’s attempt to retain water
- check ECF volume status: ddx SIADH, heart, liver, kidney ds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

hyponatremia + low plasma osmolality: Urine Osmolality > 100 mOsm; normal ECF

A
  • SIADH
  • Hypothyroidism
  • adrenal insufficiency
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

hyponatremia + low plasma osmolality: Urine Osmolality > 100 mOsm; increased ECF

A

conditions are often associated with edema and fluid overload

  • CHF
  • Cirrhosis
  • nephrotic syndrome
  • renal insufficiency
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

hyponatremia + low plasma osmolality: Urine Osmolality > 100 mOsm; decreased ECF

A

1) Check urinary Na+ concentration

urinary sodium (Na+) is less than 10:
- extra-renal loss: past vomiting and diuretic use

urinary sodium (Na+) is greater than 10:
- sodium wasting nephropathy
- hypoaldosteronism
- current diuretic use
- active vomiting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

hyponatremia tx

A

Key in treatment is RATE of sodium infusion
- DO NOT CORRECT > 10-12 mM in first 24 hrs
- too quickly: rapid shift of sodium levels may destroy myelin sheath = Osmotic Demyelination

asymptomatic: 0.5-1.0 mM/hr

emergent sx:
- give hypertonic saline and increase 1-2 mmol/L for 3-4 h OR until sx improvement
- then: 0.5-1.0 mM/hr

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Hypernatremia: s + s

Study These Flashcards
A

Depends on Plasma Na+ levels and rate of Na+ decrease
- brain has mechanisms to protect ICF volume

-Mild: Thirst/Polyuria
- Moderate: Weakness
- Severe: Neurologic Deficits & Altered Mental Status
- Very Severe: Seizure & Coma

22
Q

Hypernatremia: what would you expect body to do

Study These Flashcards
A

Renal: Kidneys will try to make maximally concentrated urine with minimal volume
- <500 mL/day
- >800 mOsm

Hypothalamus: THIRST response is activated to maintain adequate intake of free water

23
Q

Hypernatremia: treatment

Study These Flashcards
A

Correct underlying cause

Correct water deficit:
- SLOW REHYDRATION- Risk of Osmotic Demyelination
- Plasma Sodium should decrease no more than 0.5 mM/hr or 12 mM/24 hours
- Enteral replacement is ideal

24
Q

Nephrogenic Diabetes Insipidus: definition and causes

Study These Flashcards
A

Definition: Renal resistance to ADH

Inherited cause: Genetics

Acquired causes:
- Medications: Lithium (treatment for bipolar ds)
- Hypercalcemia
- Hypokalemia
- Pregnancy

25
Central Diabetes Insipidus: definition and causes
Definition: Impairment of ADH secretion Most common cause: Destruction of Pituitary - Oftentimes nonreversible
26
DI treatment: central vs nephrogenic
Central: - intranasal desmopressin - ADH secreting drugs - low salt diet - thiazide diuretics Nephrogenic: - treat underlying cause - NSAIDS - if taking lithium: amiloride - low salt diet - thiazide diuretics
27
Hyper/Hypokalemia are assessed with fluid draws:
Venous blood * Arterial Blood Urine Blood Draw Tips: - Avoid drawing from a limb with an IV - If must, draw the blood distal to IV site - Use as large bore needle as possible to prevent hemolysis
28
Potassium: GI system
- we consume 40-120 mM per day and 90% is ABSORBED in GI - 10% GI loss: increased in renal failure and diarrhea
29
Potassium summary
most abundant intracellular cation - ICF: ECF = 38:1 - normal plasma: 3.5-5 - normal intracellular: 150 avg (muscle cells have more) - normal extracellular: 30-70 Muscle has way more K+ in each cell - Issue: pt that falls and rhabdo with crush injury -> can release LARGE AMOUNTS OF K+*****
30
31
Potassium: renal excretion
- filtered K+: GFR x serum potassium concentration - passive reabsorption (90%): proximal convoluted tubule and loop of henle - active secretion: distal convoluted tubule and collecting ducts by PRINCIPAL CELLS - secretion and reabsorption rates change based on K+ concentration and ALDOSTERONE
32
How to insulin and Beta 2 agonists affect K+ levels?
Insulin: - directly and indirectly increases K+ levels through Na+-K+ ATPase β2 Agonists: - stimulates Na+-K+ ATPase = ↑ ICF K+
33
What increases or decreases Na/K ATPase
Increase: higher intracellular Na+ Decrease: - digoxin toxicity - CHF - Chronic renal failure
34
Hyperkalemia: decreased K+ excretion causes
- renal failure - interstitial nephritis - sickle cell ds - hypoaldosteronism - durgs: ACEi, trimethoprim, NSAIDs, spironolactone, triamterene
35
Hyperkalemia: potassium shift causes
Rhabdomyolysis & Hemolysis = Release of ICF K+** Exercise** - more exercise = more K+ release - strenuous + beta blocker: UP TO 4 mmmol/L -> need cardiac rehab others: - burns - sepsis - hypertonicity - insulin deficiency - metabolic acidosis - drugs: digoxin, beta blockers, succinylcholine, arginine
36
hyperkalemia sx
Often asymptomatic If symptomatic: - MSK: Weakness; K = muscle issues - Cardio: Palpitations - GI: Constipation
37
hyperkalemia tx - acute
Treat underlying cause! - HOWEVER: do not delay treatment to find the cause As opposed to Sodium, MUST have rapid correction of K+ - Due to risk of Cardiac Abnormalities acute tx: - calcium gluconate - glucose and insulin - albuterol - diuretics - kayexalate - hemodialysis
38
hyperkalemia labs + dx
Dx: serum K+ > 5 others: - BUN/Cr: Determine if renal - Serum glucose - EKG: PEAKED t waves - Urinalysis
39
hyperkalemia tx - chronic
Dietary Restriction Removal of Iatrogenic cause Loop Diuretics Treat underlying cause: - ex: Fludrocortisone for hypoaldosteronism
40
hypokalemia: causes
- renal potassium loss - potassium shift into ICF - decreased K+ intake - extrarenal potassium loss - sample error
41
hypokalemia: causes of renal potassium loss
Excess Aldosterone: - Hyperaldosteronism - Cushings - Renovascular HTN ↑ Renal Flow at distal nephron: - Diuretics Hypomagnesemia: Mg2+ is needed to transport K+ Renal Tubular Acidosis Genetic Disorder - Bartter’s Syndrome - Liddle’s Syndrome
42
hypokalemia: causes of K+ shift into the cell
- excess insulin - alkalosis - beta adrenergic excess - hypokalemic periodic paralysis
43
hypokalemia: extrarenal loss causes
- vomit/diarrhea - villous adenoma - zollinger-ellison syndrome
44
hypokalemia sx
May be asymptomatic If Symptomatic: - Muscle cramps - Fatigue - Weakness - Constipation
45
hypokalemia signs
If Diuretics = ↓ BP If Gitelman's Syndrome = ↓ BP If Hyperaldosteronism = ↑ BP Irregular HR Paralysis Decreased bowel sounds
46
Serum K+ < 3.5 mM what other labs/tests to check to help with dx and tx?
hypokalemia BUN:Cr: To assess renal function Glucose Magnesium EKG: Presence of U WAVES ABG
47
hypokalemia tx: who do you give potassium supplements to
Stable: Treat underlying cause; low Na+ diet, d/c meds Potassium replacement: - Intolerant to low Na+ diet - Pt with nausea, vomiting, diarrhea - Pt unable to stop Diuretics or Laxatives - Pt with drug-induced hypokalemia
48
24-Hr Urine: hypokalemia results
If [K+]Urine < 30 mM = Extrarenal [K+]Urine > 30 mM = Renal
49
Potassium Replacement
in general: 40-100 mmol/day = effective - Oral Replacement is preferred if IV: - K+ suspended in NS - No faster than 40 mM/hr -> faster will cause cardiac arrest, K+ is irritating and pts will complain that it is burning - If 20-40 mM/hr, MUST monitor cardiac
50
Magnesium replacement in hypokalemia
only indicated if hypokalemia is refractory to tx AND: - CHF - Chemo (cisplatin) - digoxin toxicity - loop diuretics
51
hypokalemia f/u
Emergency: check electrolytes every 1-2 h Stable: check 4-6h after tx; check daily Outpatient setting: check weekly until stable; then check monthly or quarterly depending on pt compliance

nephrology (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions