Clin Med - Fernandez 1

drraythe's version from 2016-02-03 15:43


Question Answer
What determines the movement of water in body compartments?The osmolality of the compartment
(Hypernatremia) what is NORMAL reference rang for sodium? At what level is a hypernatremia considered severe?NORMAL: 145 – 155 mEq/L (*remember there is some variation btwn species & analyzers)
SEVERE: >180mEq/L
What are the 2 ways you'd get a HyPERnatremia? (General) & which is more common?(1) FREE WATER LOSS (*more common)
(2) Excess sodium intake or retention
4 reasons you might see a free water deficit?(1) No water access
(2) ECF losses (vomiting, diarrhea, polyuria)
(3) Metabolic loss (such as a horse sweating, or a dog locked in a hot car)
(4) Diabetes insipidus PTx w/o water access (cant reabsorb their H2O))
6 reasons there might be a sodium excess?Ingestion of large quantities of sodium
Sodium bicarbonate
Beef jerky
Salted meats
Explain why you see CNS signs when there is a rapid & severe rise in sodium?Water moves out of relatively hypo-osmolar space (ICF) to hyperosmolar space (ECF), which makes cells shrink. This inclds NERVES, which leads to Obtundation, Seizures, Coma, Death
In a chronic HYPERnatremia, how does the brain physiologically adapt? Explain how this ties into your therapyThe brain cells sense a shrinkage & ↑ intracellular osmolarity by generating idiogenic osmoles. This czs water to move back into the cells. This process starts a few hours after ↑ levels of sodium & the process is complete by 24hrs. These idiogenic osmoles are the REASON you have to do therapy slowly-bc the brain has already compensated & you can flood out the neurons
Which is more common-hypo or hyper natremia?Hyper
What is the cz of hyponatremia?ALWAYS FREE WATER RETENTION IN EXCESS OF TOTAL BODY SODIUM → water intake, or impaired water excretion
What are some reasons for ↓ effective circulating volume & how does this result in HYPOnatremia?Some things which would ↓ the circulating volume would be congestive heart failure, GI loss, urinary loss, or fluid third spacing to body cavities. This sec of circulating volume results in release of ADH, which czs water retention & ↑ water intake, which ↓ (/dilutes) the sodium concentration
How does hypoadrenocortisism affect sodium levels? ExplainCzs HYPOnatremia! This is bc there are ↓ levels of aldosterone (the Na saving hormone) so there is ↓ sodium retention (ie more loss) & it also triggers ↑ water intake & retention of water to defend extracellular volume loss
How can diuretics affect Na+? ExplainThiazide & loop diuretics induce hypovolemia & low levels of K+. The body is more concerned about compensating for the K+, so there is intracellular shift for K+ w/ Na+ (leading to low serum Na+, aka HYPOnatremia!)
What is SIADH? Explain how it affects sodium levels"Syndrome of inappropriate antidiuretic hormone". This leads to water retention as a response to inappropriate ADH-too much water means you are diluting the conc of Na+, which means you have HYPOnatremia
What would be considered a SEVERE hyponatremia? (mEq/L)<120 mEq/L
What are the CS of (severe) HYPOnatremia? Explain themCNS signs!! The lack of Na in the serum means the cells are relatively hyperosmolar & water follows that gradient into the cells → cell swelling. (Interstitial & intracellular edema!)
Normal serum [K+] essential for...Neuromuscular fxn
What is the serum concentration of K+ when it is considered HYPOkalemia?Serum [K+] < 3.5 mEq/L
What are the 2 general ways that you can get hypokalemia?Redistribution, or depletion
What are 4 common clinical conditions which can lead to hypokalemia via REDISTRIBUTION?? (these are just a few examples)Metabolic alkalosis (exchange K+ in serum for H+ in the cells to try to balance pH)
Insulin administration (insulin ↑ Na+/K+ pump action, more K+ in cell & less in serum then)
Beta-agonist therapy (↑ Na/K pump, also release aldosterone from kidney so save Na & lose K)
Refeeding syndrome (During refeeding, insulin secretion resumes in response to ↑ blood sugar; resulting in ↑ glycogen, fat & protein synthesis. This process requires phosphates, magnesium & potassium which are already depleted & the stores rapidly become used up.)
What are 4 common clinical conditions which can lead to hypokalemia via DEPLETION? (There are just a few examples)Renal wasting (not able to retain K+)
Dietary-inadequate intake (I think main source is in meat?)
Diuresis (K+ losing diuretics)
Severe diarrhea
*Classic sign of a cat w/ hypokalemia?Ventral neck flexion! (Look like theyre looking at their toes)
Plantigrade stance might indicate what?Hypokalemia
Ventral neck flexion might indicate what?Hypokalemia
How does hypokalemia affect muscles?HYPOkalemia → hyperpolarized (bc it ↓ resting membrane potential which makes it farther from threshold (means MORE potassium has to flood out of cell to get same effect) ) → less excitable → MUSCLE WEAKNESS!! This will mean you'll see signs like a stiff gait, a plantigrade stance: "Hypokalemic myopathy"
How does hypokalemia affect an ECG reading?ST segment depression, prolonged QT interval (once again, hyperpolarized means harder to depol, means harder to do all the electrical stuff in the heart, so smaller & longer waves)
If there was 1 PTx who you'd think of when I say hyperkalemia, who would it be?BLOCKED CAT
What is normal serum potassium levels? When is HYPERkalemia life threatening?Serum potassium > 5.5 mEq/L. Life threatening > 7.5 mEq/L
What would be 4 (general) czs for disturbances leading to hyperkalemia?(1) ↑ intake or administration
(2) Translocation (IC to EC)
(3) Reduced renal excretion
(4) Artefactual (K+ is an intracellular ion & lysed RBCs will release it)
How does hyperkalemia affect the GI?GI upset
How does hyperkalemia affect the heart?BRADYCARDIA, ATRIAL STANDSTILL (Prolonged depolarization & repolarization)
How is hyperkalemia & the ECG related?*ECG findings do not precisely correlate w/ concentration
What are 7 CS of HYPERcalcemia?Polyuria
Bradycardia (remember, we're talking about EXTRAcellular Ca++, not intracellular)
List off some Ddx diagnoses for HYPERcalcemiaNon pathologic – Lab error
Transient – Changes in hydration
Pathologic – Hyperparathyroidism, Malignancy, Bone neoplasia, Hypervitaminosis D, Acute renal failure, Fungal dz, Excess supplementation
How might you go about diagnosing HYPERcalcemia?If you look at total serum calcium you might start to suspect hypercalcemia, but you would have to look at IONIZED calcium to confirm. Check your results w/ lab reference ranges & be sure to actually look for the underlying cz!
How does hypercalcemia affect muscles?Leads to muscle twitching
How does hypercalcemia affect the CNS?Leads to seizures/Encephalopathy
How does hypercalcemia affect the kidneys?Rapid renal decline
How does hypercalcemia affect the heart?Cardiac arrhythmias
What are the CS of a hypercalcemic crisis?Mm twitching
Rapid renal decline
Cardiac arrhythmias
5 major CS of HYPOcalcemia?Could be:
(1) NONE
(2) Muscle tremors
(3) Fasciculations
(4) Muscle cramps
(5) Behavior changes-anxious
List off 7 DDXs for HYPOcalcemia (not all, but some good examples)Chronic renal dz
Acute renal failure
Ethylene glycol intoxication
Hypovitaminosis D
Nutritional 2° hyperparathyroidism....ETC!!

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