Anion Gap Explain?

[Bathrover]

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Why is there an increased anion gap in chronic renal failure but normal in type 1 RTA if both are decreased excretion of H+ as NH4+. I thought H+ ions are not counted in the anion gap equation, can someone thoroughly explain this please =)

 

[DrEnderW]

My understanding is that it's an inability for intercalated cells to secrete H+ into the urine. The job of these cells is to secrete H+ and generate new HCO3-, which is absorbed back into the interstitium/blood. When you lose the ability to secrete H+ from the cell, you would be favoring H2CO3 in the cell. Without that H+ ion being able to be secreted and leave the cell, you aren't forming the new bicarb either (this is why urine pH is high and blood pH is low). The low bicarb would lead you to think that the anion gap would be high but I believe the body is compensating by raising the Cl- level to a point where there is a normal anion gap. This is why Type 1 RTA is a hyperchloremic metabolic acidosis.

Don't quote me on this, just my thoughts.

 

[Priapism4tooLong]

Anion gap in chronic renal failure? That's not right.

I'm not saying it couldn't happen but it's not a common cause. Chronic renal failure is mostly caused by diabetes and htn by far. Diabetic ketoacidosis can cause an anion gap ofc but I wouldn't say anion gap is caused by chronic renal failure.

edit: i am wrong, my co-worker said that metabolites accumulate when you have chronic renal failure.. causing an increased anion gap.
2nd edit: i actually knew this im just really tired.

wiki:

• Renal failure, causes high anion gap acidosis by decreased acid excretion and decreased HCO3− reabsorption. Accumulation of sulfates, phosphates, urate, and hippurate accounts for the high anion gap.

 

[spik]

Anion gap in chronic renal failure? That's not right.

I'm not saying it couldn't happen but it's not a common cause. Chronic renal failure is mostly caused by diabetes and htn by far. Diabetic ketoacidosis can cause an anion gap ofc but I wouldn't say anion gap is caused by chronic renal failure.

edit: i am wrong, my co-worker said that metabolites accumulate when you have chronic renal failure.. causing an increased anion gap.
2nd edit: i actually knew this im just really tired.

wiki:

• Renal failure, causes high anion gap acidosis by decreased acid excretion and decreased HCO3− reabsorption. Accumulation of sulfates, phosphates, urate, and hippurate accounts for the high anion gap.

It is understandable. Priapism for too long can be exhausting.

 

[razor]

My understanding is that it's an inability for intercalated cells to secrete H+ into the urine. The job of these cells is to secrete H+ and generate new HCO3-, which is absorbed back into the interstitium/blood. When you lose the ability to secrete H+ from the cell, you would be favoring H2CO3 in the cell. Without that H+ ion being able to be secreted and leave the cell, you aren't forming the new bicarb either (this is why urine pH is high and blood pH is low). The low bicarb would lead you to think that the anion gap would be high but I believe the body is compensating by raising the Cl- level to a point where there is a normal anion gap. This is why Type 1 RTA is a hyperchloremic metabolic acidosis.

Don't quote me on this, just my thoughts.

That's a pretty good explanation. It's easier for me to think of the RTAs as a bicarb problem despite their names. You either can't reabsorb bicarb (proximal RTA) or you can't make "new' bicarb (distal RTAs).

Also a general rule of thumb remember that we move bicarb across membranes via exchange w/ Cl-. This is why the bicarb deficit is balanced by Cl- increase in NAGMAs.

 

[mmgala77]

My understanding is that it's an inability for intercalated cells to secrete H+ into the urine. The job of these cells is to secrete H+ and generate new HCO3-, which is absorbed back into the interstitium/blood. When you lose the ability to secrete H+ from the cell, you would be favoring H2CO3 in the cell. Without that H+ ion being able to be secreted and leave the cell, you aren't forming the new bicarb either (this is why urine pH is high and blood pH is low). The low bicarb would lead you to think that the anion gap would be high but I believe the body is compensating by raising the Cl- level to a point where there is a normal anion gap. This is why Type 1 RTA is a hyperchloremic metabolic acidosis.

Don't quote me on this, just my thoughts.

If

 

[mmgala77]

if the anion gap is 2.5, ast is 10 and gfr is 54 with a bun of 6 and %Imm 0.5 wouldn't this be a first indicator of bone cancer as the patient just under went lung surgery for cancer a year ago. Sorry really struggling with understanding anion gap

 

[Jabbed]

Other waste products accumulate in chronic renal failure and account for the unmeasured anion increase: phosphoric, sulfuric, and uric acid AFAIR. That's not the case in the RTAs.

 

[jdh71]

Why is there an increased anion gap in chronic renal failure but normal in type 1 RTA if both are decreased excretion of H+ as NH4+. I thought H+ ions are not counted in the anion gap equation, can someone thoroughly explain this please =)

View attachment 187033

Define "chronic renal failure". Dealing with acid is basically the last thing to go, so end stage chronic renal failure will eventually give you an acidosis and a gap because of other acids it also deals with, but just having most stages of "chronic kidney disease" will not demonstrate any appreciable gap.

 

[naosansist]

Chronic renal failure is mostly caused by diabetes and htn by far. Diabetic ketoacidosis can cause an anion gap ofc but I wouldn't say anion gap is caused by chronic renal failure.

 

[jdh71]

Chronic renal failure is mostly caused by diabetes and htn by far. Diabetic ketoacidosis can cause an anion gap ofc but I wouldn't say anion gap is caused by chronic renal failure.

End stage renal failure gives you a gap acidosis.