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13 Cards in this Set
- Front
- Back
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What is a normal anion gap?
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12 +/- 2 mEq/L
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In a patient with pH of 7.27, bicarbonate serum concentration of 20 mM and a serum carbon dioxide partial pressure of 27 mmHg, are the lab values internally consistent?
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!["Confirm internal consistency by checking if [H+] is within 10% of 24*(PCO2/HCO3).
[H+]=10^(-7.27) =~ 53 nmol/L (RoT=~ 80-27=53)
24*(27/20)= 32.4
Since 32.4 is more than 10% different from 53, the values are not consistent. F...](https://images.cram.com/images/upload-flashcards/61/51/55/2615155_m.png)
Confirm internal consistency by checking if [H+] is within 10% of 24*(PCO2/HCO3).
[H+]=10^(-7.27) =~ 53 nmol/L (RoT=~ 80-27=53) 24*(27/20)= 32.4 Since 32.4 is more than 10% different from 53, the values are not consistent. Fire your lab. Don't forget to bring your calculator to the exam! |
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What is the primary disturbance in the 4 acid-base disorders and what is the normal secondary compensation response?
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What kind of acid/base disorder does a patient with a serum pH of 7.5, normal bicarbonate levels and low PaCO2 levels have?
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High pH -> Alkalemia
Low PaCO2 -> Respiratory Alkalosis (Normal HCO3 -> no renal compensation.) |
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What kind of acid/base disorder does a patient with a serum pH of 7.25, low bicarbonate levels and normal PaCO2 levels have?
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Low pH -> Acidemia
Low HCO3 -> Metabolic Acidosis (Normal PaCO2 -> no respiratory compensation.) |
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Does a patient with a pH of 7.27 HCO3 of 12 mM, and carbon dioxide partial pressure of 12 mmHg have appropriate secondary compensation for his primary acid-base disorder? (first determine primary disorder)
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Normal pH is 7.35, so he's acidotic.
Normal HCO3 is 24 mM, normal PaCO2 is 40 mmHg. There is a decrease in both HCO3 and PaCO2; since the patient is acidotic, the decreased bicarbonate indicates it's a metabolic acidosis, the decreased CO2 indicates that the patient is compensating by hyperventilating (compensatory respiratory alkalosis). |
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What does the Anion Gap measure?
How is it calculated? What is a normal value? |
It is an estimate of the quantitiy of unmeasured anions in the serum.
It is calculated by taking the sum of all measured cations and taking the difference of the sum of all anions in the serum. |
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What might an increased anion gap indicate, in the context of a metabolic acidosis?
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An increased anion gap indicates that there are more unmeasured anions in the serum, which are most likely weak acids such as:
MUDPILES methanol uremia diabetic ketoacidosis propylene glycol isoniazid lactic acidosis ethylene glycol salicylates |
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What might cause a normal anion gap metabolic acidosis (NAGMA)?
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In NAGMA, the loss of HCO3- is compensated by an increase in Cl-. This happens in states like:
-GI loss of HCO3 (e.g. diarrhea) -Renal excretion of HCO3 (Renal Tubular Acidosis(RTA)) -Drug use. |
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What do you look for if you have a low anion gap?
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Hypoalbuminemia.
How much does the anion gap go down with each 10 g/L of serum albumin? 4 |
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What is a normal renal response to metabolic acidosis?
and What is the problem if that's not the case? |
The urine should be free of HCO3- and high in NH4+.
Renal tubular acidosis |
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In a patient with urine sodium of 10 mM, potassium 15 mM, Cl 7 mM, urea 15 mM, and a measured urine osmolarity of 300 mM, calculate the urine net charge and the osmol gap.
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!["For urine net charge, you compare [Cl-] with [Na+] + [K+].
[Cl-] = 7 mM; [Na+] + [K+] = 10+15= 25 mM
Since 7 << 25 mM, we know that there is a net positive measured charge, implying that there is little unmeasured cation (ammonium).
If [...](https://images.cram.com/images/upload-flashcards/61/52/00/2615200_m.png)
"For urine net charge, you compare [Cl-] with [Na+] + [K+].
[Cl-] = 7 mM; [Na+] + [K+] = 10+15= 25 mM Since 7 << 25 mM, we know that there is a net positive measured charge, implying that there is little unmeasured cation (ammonium). If [Cl-] was greater than [Na+] + [K+], then there would be a large quantity of unmeasured [NH4+], most likely, since it's the next-most-common cation in urine. This is all based on the fact that urine is electroneutral. |
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What are the two major types of Renal Tubular Acidosis (RTA)?
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Classified based on the portion of the tubule effected:
-Type 1: Distal, results from inadequate excretion of NH4+. -Type 2: Proximal, from inadequate absorption of filtered HCO3 in the proximal tubule. - Type 4: Aldosterone deficiency or resistance (not an actual RTA, but lumped in because of similar presentation) |
