Nephro-Acid Base

Question 1

Steps to analyze Acid-Base

Answer 1

1. Look at serum bicarb–is it a primary acidosis or alkalosis?
2. Look at the CO2-is it respiratory or metabolic?

Question 2

In a metabolic acidosis, what do you look at first?

Answer 2

You look for an anion gap

AG=Sodium-(Cl+Bicarb)

Question 3

What is the pathology behind AG metabolic acidosis?

Answer 3

Unmeasured organic anion, such as lactate

Question 4

What is the pathology behind non-AG metabolic acidosis?

Answer 4

Bicarb loss

Question 5

What is a normal AG?

Answer 5

8-10

Question 6

How does serum albumin impact anion gap?

Answer 6

Decreased albumin, decreases the anion gap, whereas ppl with high albumin have a higher anion gap

Corrected AG= AG+(2.5 x (normal albumin-measured albumin))

Question 7

When there is a change in anion gap from albumin, how do you correct the bicarb?

What happens if the measured bicarb is less than the normal bicarb?

Answer 7

You correct the bicarb by…

Corrected bicarb=24 mEq - (change anion gap from albumin)

You get a concomitant metabolic alkalosis if the measured bicarb is greater than the corrected one

You have a concurrent non-anion gap metabolic acidosis if the measured bicarb is less than the corrected one

Question 8

What are the two methods to see if there is a concurrent mixed AB disorder?

Answer 8

1. corrected bicarb, if albumin high or low

2. delta delta

Question 9

How is the delta delta calculated?

Answer 9

It is the the change in anion gap divided by the change in the bicarb.

Ratio <1: reflects the presence of concurrent normal AG metabolic acidosis

Ratio >2: indicates the presence of a metabolic alkalosis

Question 10

Causes of an increased anion gap metabolic acidosis

Answer 10

MUDPILES
methanol
uremia
diabetic keotacidosis
polyethylene glycol
ingestions: Tylenol, salicylates, 
Lactic acidosis
Ethylene glycol
Salicylate toxicity

Question 11

What are the causes of type A, B, and D lactic acidosis?

Answer 11

TYPE A: Tissue hypoperfusion

TYPE B: propofol, metformin, hematological malignancy (seen in high grade b-cell lymphomes from anaerobic metabolism of cancer cells)

TYPE D: short bowel syndrome, undigested carbohydrates in the colon are metabolized to D-lacatate

Question 12

What are the clinical manifestations of Type D Lactic Acidosis? What is the treatment? How is it diagnosed?

Answer 12

Intermittent confusion, slurred speech, ataxia, increased AG metabolic acidosis with NORMAL serum lactate level

TREATMENT: Antibiotics directed toward bowel flora; restriction of dietary carbs

DIAGNOSIS: Measurement of D-lactate

Question 13

What is the pathology of ethylene glycol ingestion? Clinical symptoms? Treatment?

Answer 13

glycolic acid accumulation; calcium oxalate precipitation in renal tubules and crystals in the urine

flank pain; nephrocalcinosis; CV collapse; pulmonary edema

Treatment: HD, FOmepizole, sodium bicarbonate and pyridoxine/thiamine in suspected ethylene glycol toxicity

Question 14

What is the pathology of methanol ingestion? Clinical symptoms? Treatment?

Answer 14

Formic acid ingestion

Impaired vision/ blindness mediated by formic acid’ papullemeda; mydriasis; afferent pupillary defect; abdominal pain; pancreatitis

Treatment: HD, fomepizole, sodium bicarbonate

Question 15

What is the pathology of propylene glycol toxicity? Clinical symptoms? Treatment?

Answer 15

It is used a lot to dilute medications and so large doses accidentally given (such as with lorazepam) can cause it

You get an AKI, AG metabolic acidosis with increased plasma osmolal gap

Treatment: d/c the IV infusion

Question 16

What is the pathology of salicylate toxicity?

Clinical symptoms? Treatment?

Answer 16

Salicylate anion accumulation

Clinical: Tinnitus, tachypnea, impaired mental status, cerebral edema, fatal brainstem herniation… lactic acidosis.. lots of things…

Treatment: IV glucose (100mL of 50% dextrose) in adults when MENTAL STATUS CHANGES ARE PRESENT irrespective of plasma glucose level

HD for AKI, imparted mental stately, cerebral edea, severe AG MA, pulmonary edema, salicylate >80

Vitamin K for increased INR

Question 17

Acetaminophen toxicity: what is the pathology? clinical symptoms? treatment?

Answer 17

common in those who are critically ill, poor nutrition, liver disease, CKD, and in vegetarians;

clinical: impaired mental status, high concentrations in the urine of pyroglutamate
treatment: discontinue acetaminophen, sodium bicarb

Question 18

What next step do you take if you have a NAGMA?

Answer 18

Check urine anion gap!

Uag=(Una+Uk)-Ucl

Causes of negative urine AG: ammonium chloride ingestion, diarrhea/acidosis, Type 2 proximal RTA

Causes of positive urine AG: Type I RTA, Type 4 RTA

Question 19

What is a type 2 RTA? Why does it occur?

Answer 19

Defect in the proximal tubule results in a diminished ability to reabsorb filtered bicarb.

Causes: hereditary, sporadic/transient, Fanconi syndrome

Usually part of Fanconi syndrome

Treat with a thiazide diuretic

Question 20

What is a type 1 RTA? Why does it occur? How is it treated?

Answer 20

Hypokalemic, distal RTA

people with a type I RTA are unable to acidify the pH of their urine

Treat with potassium citrate

Question 21

Type 4 RTA? What is it? Why does it occur? How is it treated?

Answer 21

Hyperkalemic, Distal RTA

Drug induced very common: seizure meds, ACE-Inhibotrs, TMP, heparin,

Aldosterone deficiency or resistance

Treatment: treat hyperkalemia, stop meds causing it, restrict potassium

Question 22

What is the first thing you do if someone has a metabolic alkalosis?

Answer 22

You assess blood pressure and volume status to create differential

Question 23

Metabolic alkalosis, increased extracellular fluid, low blood pressure?

Answer 23

CHF, cirrhosis, nephrotic syndrome

Question 24

Metabolic alkalosis, normal/low blood pressure, urine chloride is low <15?

Answer 24

vomiting

Question 25

Metabolic alkalosis, normal/low blood pressure, urine chloride is low >15?

Answer 25

active diuretic use
hypokalemia
hypomagnesemia 
Aminoglycoside toxicity
Bartter/Gitelman syndrome

Question 26

Metabolic alkalosis, blood pressure increased, urine sodium and urine chloride high >15?

Answer 26

Renin secreting tumor
Malignant hypertension
Renovascular hypertension
Primary hyperaldosteronism
Mineralcorticoid excess (Ectopic ACTH syndrome)

Question 27

Causes of Respiratory alkalosis

Answer 27

ENHANCED RESPIRATORY DRIVE
sepsis, hepatic failure, anxiety, psychosis, pregnancy, nicotine, salicylates

HYPOXEMIA
high altitude, severe anemia, hypotension, chronic heart failure, pulmonary parenchymal disease

PULMONARY DISEASE WITH THORACIC STRETCH RECEPTOR STIMULATION
pneumonia, ARDS, PE, hemothorax, pneumothorax, pulmonary edema