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Clinical Medicine 3 > Lecture 15 (Renal)-Exam 5 > Flashcards

Lecture 15 (Renal)-Exam 5 Flashcards

1
Q

Anion Gap
* What is this?
* What is the equation?
* What is normal range?
* High indicated what?
* Low” is relatively rare but serves as what?

A
  • A measurement between the sum of routinely measured cations and routinely measured anions in the blood
  • The anion gap = (Na+±K+) – (Cl- + HCO3-)
  • (Sodium + Potassium) – (Chloride + Bicarb)
  • Normal falls between 3 and 12 mEq/L->Lab dependent (I’ve seen as high as 16 reported as normal)
  • High indicates metabolic acidosis
  • “Low” is relatively rare but serves as an indication of the presence of abnormal positively charged protein
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2
Q

Low Anion Gap
* Recheck labs-> why?
* What are causes?
* Overproduction of what?

A
  • Recheck labs – may be a lab error
  • Causes – Hypoalbuminemia (low level of protein in blood) found in kidney and liver disease, infection, burns, hypothyroidism and cancer
  • Overproduction of IgG can lead to low anion gap (think multiple myeloma, inflammatory conditions)
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3
Q

Low Anion Gap
* _ intoxication
* What drug?
* A large increase in what?

A
  • Bromide intoxication
  • Lithium
  • A large increase in calcium and magnesium
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4
Q

ABG
* What test do you need to do?
* You can obtain the information you need for acid/base disorders from other methods: (4)

A

Recall Allen test

You can obtain the information you need for acid/base disorders from other methods:
* Peripheral venous
* Central venous
* Intraosseous
* Capillary

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5
Q
A
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6
Q

pH
* Negative logarithm of what?
* What is a high and low pH?
* Serum pH below 6.7 or higher than 7.6 is what?

A
  • Negative logarithm of the hydrogen ion concentration in the blood
  • Alkalosis- pH is elevated, Acidosis- pH decreased
  • Serum pH below 6.7 or higher than 7.6 is unsustainable and will eventuallyresult in death if not corrected
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7
Q

PcO2
* What is it?
* measurement of what?
* What causes low CO2?

A
  • Partial pressure of carbon dioxide
  • Measurement of VENTILATION
  • Faster, deeper breathing = low Co2
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8
Q

PcO2
* Affected by what?
* CO2 is the strongest driver of what? Very important in who?

A
  • Affected by metabolic processes as well as compensation
  • CO2 is the strongest driver of the ventilation reflex and WILL NOT allow hypoventilation to compensate for metabolic alkalosis
  • Very important in COPD patients and Oxygen supplementation
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9
Q

HCO3
* measurement of what?
* Indirect measurement is what?
* Directly proportional to what?
* Can compenstate for what?

A
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10
Q

PO2
* What is it?

A

Pressure of oxygen dissolved in the plasma

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11
Q

Base Excess / Deficit
* Calculated measure based on what? (3)
* Measures amount of what?
* Negative base excess (ie deficit) =
* Positive base excess =

A
  • Calculated measure based on pH, PCO2, hematocrit
  • Measures amount of buffering ions in the blood (the most important of which is bicarb)
  • Negative base excess (ie deficit) = indirect metabolic acidosis
  • Positive base excess = metabolic alkalosis or compensation for respiratory acidosis
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12
Q

Terminology
* Acidosis-
* Acidemia-

A
  • Acidosis- PROCESS that lowers the pH
  • Acidemia- describes the pH itself being low
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13
Q

Acid Base Disturbances (Basics)
* Respiratory acidosis-
* Respiratory alkalosis-
* Metabolic acidosis-
* Metabolic alkalosis-

A
  • Respiratory acidosis- ineffective ventilation > high CO2 > low pH > acidemia
  • Respiratory alkalosis- fast, deep breathing > low CO2 > high pH > alkalemia
  • Metabolic acidosis- decreased bicarbonate retention > low serum bicarbonate > low pH > acidemia
  • Metabolic alkalosis- increased bicarbonate retention > high serum bicarbonate > high pH > alkalemia
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14
Q

Acid/Base Disturbances IMPORTANT
* It is either what?
* You list both if it what?

A
  • You list both if it is “partially” compensated
  • In partial compensation, the pH is not yet corrected.
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15
Q
A
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16
Q

Approach to Acid/Base Disorders
* What is step one?

A
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17
Q

Approach to Acid/Base Disorders
* What is step two?

A

Look at the relationship between the pH and the pCO2 level

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18
Q

Step 2: Respiratory or Metabolic
* If primary respiratory disorder:
* In metabolic:
* For example, if you see a very high CO2 and a low pH, this is likely what?
* If you see a very low CO2 and a low pH, this is likely what?

A
  • If primary respiratory disorder, pH and PCO2 would be expected to be opposite
  • In metabolic, pH and PCO2 would be expected to change in same direction
  • For example, if you see a very high CO2 and a low pH, this is likely a respiratory acidosis
  • If you see a very low CO2 and a low pH, this is likely a metabolic acidosis
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19
Q

Approach to Acid/Base Disorders
* What is step 3?

A
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20
Q

Approach to Acid/Base Disorders
* What is step four?

A
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21
Q
A
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22
Q

how long does kidneys and lungs take to compensate?

A
  • Remember: It takes the kidneys a while (starts at 6-12 hours, can last days) to compensate when there is a primary respiratory issue
  • The lungs compensate quickly for primary metabolic instances (hypo/hyperventilation)
23
Q
A
24
Q

Normal Responses to Acid/Base Disturbance
* Respiratory- acidosis causes what?
* Metabolic- acidosis causes what?
* In alkalosis, what occurs?

A
  • Respiratory- acidosis causes increased minute ventilation (blows of acid) which lowers CO2 and therefore decreases pH
  • Metabolic- acidosis causes kidneys to excrete more hydrogen ions and retain bicarbonate
  • In alkalosis, the opposite compensation occurs
25
Q

Respiratory Acidosis
* Any situation where what is reduced?
* Caused by what?
* Appropriate metabolic compensation is what?

A
  • Any situation where reduced minute ventilation would occur
  • Caused by hypercapnia
  • Appropriate metabolic compensation is increase of 2-5mEq/L HCO3 for every increase of 10 mmHg PCO2
26
Q

Respiratory Alkalosis
* Increased what?
* Most often what?
* Special mention of what?

A
  • Increased minute ventilation > decreased CO2 levels
  • Most often hyperventilation
  • Special mention of salicylate (ASA) toxicity
27
Q

Respiratory Alkalosis
* also consider what?
* Symptoms?
* Expect HCO3 to decrease by what?

A
  • Also consider CVA, increased ICP, pregnancy, hyperthyroidism, anemia
  • Symptoms of paresthesia, muscle cramping, lightheaded, syncope
  • Expect HCO3 to decrease by 2-5mEq/L per 10 mmHg decrease in PCO2
28
Q

Metabolic Alkalosis
* What are the 3 main classes?

A
  • Volume contraction (responds to saline)
  • Volume expanded (does not respond to saline)
  • Unclassified
29
Q

Metabolic Alkalosis
* What are sxs? (4)
* Can be treated with what?

A
  • In the rare severe cases, symptoms include tetany, seizures, altered mentation, dysrhythmias
  • Can be treated with acetazolamide (temporary) or hydrochloric acid (EXTREMELY RARE- in consultation with nephrology)

Acetazolamide also used to pre-treat high altitude illness for those that are traveling to high altitude from sea level – interesting pathophysiology

30
Q

Metabolic Acidosis- Elevated Anion Gap
* What is mudpiles

A
  • M= Methanol, metformin
  • U= Uremia
  • D= Diabetic ketoacidosis (also consider alcoholic, starvation ketoses)
  • P= Paracetamol (APAP), Paraldehyde (anticonvulsant), propylene glycol (hand sanitizer, medication solvent, artificial tears)
  • I= Iron, isoniazid (INH/TB medication), inborn errors of metabolism
  • L= Lactic acidosis
  • E= Ethanol, ethylene glycol (antifreeze, coolants, TASTES GOOD!)
  • S= Salicylates (ASA)

Paracetamol is tylenol

31
Q

Metabolic Acidosis- Elevated Anion Gap
* What is the added CAT acronym?

A
  • C= Carbon monoxide, cyanide
  • A= Aminoglycosides
  • T= Toluene
32
Q

Metabolic Acidosis, Normal Anion Gap
* Usually less dangerous than what?
* Vast majority of cases will be what?
* Large volume of what?

A
  • Usually less dangerous than the elevated anion gap counterpart
  • Vast majority of cases will be GI losses / diarrhea (laxative abuse)->Causes bicarbonate loss
  • Large volume “normal” saline infusion
33
Q

Metabolic Acidosis, Normal Anion Gap
* What can be a cause?
* What needs to be calculated? What is it?

A
  • Renal tubular acidosis (All types have normal plasma anion gap and hyperchloremic metabolic acidosis)
  • A Urine Anion gap needs to be calculated in this case
  • To determine whether the kidney is appropriately excreting acid or whether impaired kidney acid excretion is the cause of the metabolic acidosis
34
Q

Correction of Metabolic Acidosis
* Beware correcting with bicarbonate, why?
* Correct what?
* Support what?

A
35
Q
A

The PH is high which means this is an alkalosis, the PCO2 is normal so it’s not respiratory and the bicarb (HCO3) is high so you know it is metabolic. This is METABOLIC ALKALOSIS

36
Q
A

B. Respiratory Alkalosis, Uncompensated
The primary disorder is acute respiratory alkalosis (low CO2) due to the pain and anxiety causing her to hyperventilate. There has not been time for metabolic compensation.

37
Q
A

D. Metabolic Alkalosis, Uncompensated
The primary disorder is uncompensated metabolic alkalosis (high HCO3 -) and pH being out of normal range. As CO2 is the strongest driver of respiration, it generally will not allow hypoventilation as compensation for metabolic alkalosis.

38
Q
A

D
The clinical situation most likely to present with this acid-base disorder is salicylate toxicity. Central hyperventilation from salicylate will cause the respiratory alkalosis; salicylate itself will cause the anion gap metabolic acidosis; and vomiting will cause the metabolic alkalosis.

39
Q

What is the patho of intercalated cells?

A
40
Q

What is the patho of proximal renal tubules?

A

Acetazolamide is a CAHI (Carbonic anhydrase inhibitor) which prevents bicarb reabsorption leading to acidosis

41
Q

Calculating the Urine Anion Gap
* Increased renal NH4Cl excretion to enhance what? Why?
* Used in what?
* What is the calculation of urine anion gap?
* Urine anion gap gives a rough idea of what?
* Ammonia is excreted in the urine as what? What is the issue?

A
42
Q

Calculating the Urine Anion Gap
* The idea is this:
* Negative gap =
* Positive gap =
* NOT useful in what?

A
  • The idea is this: loss of base through GI tract > kidneys excrete more NH4Cl> NH4 excretion produces Cl- ions in the urine as well> creates a negative urine anion gap (ANIONS PREDOMINATE)
  • Negative gap = more ammonia/Cl in the urine = diarrhea / GI/renal losses of bicarb
  • Positive gap = minimal ammonia in the urine = Renal tubular acidosis
  • NOT useful in AGMA because other anions besides NH4+/Cl are present in the urine
43
Q

the amount of chloride in the urine reflects the amount of what?

A

the amount of chloride in the urine reflects the amount of ammonium present, and the urine anion gap can be used as an indicator of the ability of the kidney to excrete acid

44
Q

Renal Tubular Acidosis Summary
* RTA should be suspected when ?
* A negative urine anion gap (Cl- much greater than Na+/K+) suggests what?
* A positive urine anion gap (Cl- less than Na+/K+) is indicative of what?

A
45
Q

Distal Renal Tubular Acidosis (Type I)
* What happens with potassium?
* Aldosterone cannot influence what?
* Failure to produce what? What is the result?

A
  • Hypokalemic (failure of Na/K/ATPase pumps)
  • Aldosterone cannot influence new HCO3 generation due to damage in alpha-intercalated cells
  • Failure to produce ammonia (inadequate generation of new HCO3), unable to excrete acid (urinary excretion of NH4Cl is decreased) and therefore raises pH of urine
46
Q

Distal Renal Tubular Acidosis (Type I)
* Despite acidosis, the urine cannot be what?
* Causes what?
* Autoimmune diseases are most common causes:

A
  • Despite acidosis, the urine cannot be fully acidified (urine pH > 5.5), and increased K secretion is noted in urine, with relative serum hypokalemia
  • Causes Positive (+) Urine Anion gap
  • Autoimmune diseases are most common causes: SLE, Sjogren, RA etc.
47
Q

Proximal Renal Tubular Acidosis (Type II)
* What happens with potassium?
* What is lost in urine? What is the proximal tubules unable to do?
* Can have either what?

A
  • Hypokalemic
  • Cations Na+ and K+ lost in the urine with HCO3, and proximal tubules (90%) are unable to reabsorb filtered HCO3 back
  • See alkalotic urine from HCO3 leak and serum metabolic acidosis
  • Can have either Positive (+) OR Negative (-) Urine Anion Gap (MORE OFTEN IT IS NEGATIVE)
48
Q

Proximal Renal Tubular Acidosis (Type II)
Why can you have either Positive (+) OR Negative (-) Urine Anion Gap?

A
  • Early you have HCO3 excretion loss in PCT and relatively basic urine due to bicarbonaturia. When serum bicarbonate drops below 15, then DCT reabsorbs some urine HCO3 back into serum, causing relative and indirect acidification of urine and shifting the urine anion gap to negative.
  • Acidification occurs because of reabsorption of distal HCO3 (10%), not due to acid excretion
49
Q

Proximal Renal Tubular Acidosis (Type II)
* Potassium secretion occurs due to what?
* What is the most common cause?

A
  • Potassium secretion occurs due to osmotic diuresis (from too much HCO3) leading to serum hypokalemia, and urine hyperkalemia
  • Hypergammaglobulinemia is most common cause: MM; also acetazolamide can inhibit CAH
50
Q

Mixed RTA (Type III)
* Usually stemming from what?
* Mostly affecting children from where?
*

A
  • Usually stemming from mutations of carbonic anhydrase
  • Mostly affecting children from Arabic, North African, and Middle Eastern descent
51
Q

HyperK Renal Tubular Acidosis (Type IV)
* Most common type of RTA in clinical practice usually stemming from what?
* Dysfunction of what?
* Stems from what? What does that impair?

A
  • Most common type of RTA in clinical practice usually stemming from diabetic nephropathy
  • Dysfunction of cortical collecting duct, impairing acidification of urine and potassium secretion
  • Stems from aldosterone deficiency or resistance, that impairs distal nephron Na+reabsorption and therefore K+and H+excretion.
52
Q

HyperK Renal Tubular Acidosis (Type IV)
* What does it cause?
* What is the the MCC?

A
  • Causes Positive (+) Urine Anion gap with urine/serum hyperkalemia
  • Hyporeninemic hypoaldosteronism is the most common cause
53
Q
A

A: Identify laxative abuse as a cause of a normal anion gap metabolic acidosis.

Clinical Medicine 3 (27 decks)

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