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What Can Cause And What Is The Significance Of A
Question: what can cause and what is the significance of a high anion gap. I have analyzed my labwork and over the last 7 years my anion gap has been as high as 18 and as low as 7. I know metabolic acidosis is the reason for a high anion gap but how can there be metabolic acidosis with a normal bicarbonate level. Doesnt your bicarbonate level have to be low since the blood is more acid base? For example on my last annual these were my values and leads to an Anion Gap of 18.. Bicarbonate - 25 (22 to 29) Sodium - 140 (135 to 145) Chloride - 97 (96 to 106)
Brief Answer:
It seems a false high anion gap
Detailed Answer:
Hello and welcome to Ask A Doctor service.
I have reviewed your query and here is my advice.
Anion gap is calculated from values of sodium, chloride and bicarbonate. We subtract a sum of chloride and bicarbonate from sodium value. Though its said that normal anion gap is between 8 to 12 meq/L but I tend to disagree. The anion gap could be upto 28 meq/L with normal values of ions. That is, if sodium was upto the higher side of normal and chloride and bicarbonate were on lower side of normal, then anion gap can be upto 28 but there is no clinical problem.
On the contrary, if metabolic acidosis is present, then it can quickly go into compensation and bicarbonate may become near normal but I do not expect it to become completely normal in compensation. So its not a compensated metabolic acidosis.
Practically speaking, if there is no history of diabetes, salicylate ingestion, kidney failure, ethylene gycol or methanol poisoning, then no need to get worried about it.
There are numerous causes for false high or low anion gap. Some causes are high albumin levels, medicines like sodium penicillin or sodium citrate, increased other negatively charged ions, etc.
If the worry is still there, then upload your air blood gas values, and any recent reports showing glucose levels, kidney function test and urine analysis.
Hope this helps. Let me know if I can assist you further.
Dr Vaishalee
It seems a false high anion gap
Detailed Answer:
Hello and welcome to Ask A Doctor service.
I have reviewed your query and here is my advice.
Anion gap is calculated from values of sodium, chloride and bicarbonate. We subtract a sum of chloride and bicarbonate from sodium value. Though its said that normal anion gap is between 8 to 12 meq/L but I tend to disagree. The anion gap could be upto 28 meq/L with normal values of ions. That is, if sodium was upto the higher side of normal and chloride and bicarbonate were on lower side of normal, then anion gap can be upto 28 but there is no clinical problem.
On the contrary, if metabolic acidosis is present, then it can quickly go into compensation and bicarbonate may become near normal but I do not expect it to become completely normal in compensation. So its not a compensated metabolic acidosis.
Practically speaking, if there is no history of diabetes, salicylate ingestion, kidney failure, ethylene gycol or methanol poisoning, then no need to get worried about it.
There are numerous causes for false high or low anion gap. Some causes are high albumin levels, medicines like sodium penicillin or sodium citrate, increased other negatively charged ions, etc.
If the worry is still there, then upload your air blood gas values, and any recent reports showing glucose levels, kidney function test and urine analysis.
Hope this helps. Let me know if I can assist you further.
Dr Vaishalee
Above answer was peer-reviewed by :
Dr. Chakravarthy Mazumdar
I actually never had a blood gas done. My Kidney function is also normal. GFR is always more than 90. Do you think I should ask for a blood gas done. If I had acidosis for a long time wouldnt I be be very sick. Also dont XXXXXXX diabetes. Fasting Glucose is less than 100 and A1C is normal. Since the anion gap isnt reported on my labs I calculated on my own. my doctor never mentioned anything about it. I am assuming since my bicarbonate values fluctuate between 25- 28 its impoasible to have acidosis. It looks like my anion gap is a bit jigh because my chloride is at the bottom of thebregerence range.
Brief Answer:
Yes you are correct
Detailed Answer:
Hi again
You are correct in assuming that there is no acidosis as all the possible causes have been ruled out. But it cannot be ruled out on the basis of symptoms because symptoms can vary with the cause, its duration and severity of the disease. Sometimes it may be asymptomatic. Or there maybe non-specific symptoms like weakness, confusion etc.
If there is no intake of aspirin, ethylene glycol (in anti-freeze formulations) or methanol (mixed in alcohol), then causes have been ruled out. Then we can safely assume that high anion gap is due to other causes (not related to acidosis).
Dr Vaishalee
Yes you are correct
Detailed Answer:
Hi again
You are correct in assuming that there is no acidosis as all the possible causes have been ruled out. But it cannot be ruled out on the basis of symptoms because symptoms can vary with the cause, its duration and severity of the disease. Sometimes it may be asymptomatic. Or there maybe non-specific symptoms like weakness, confusion etc.
If there is no intake of aspirin, ethylene glycol (in anti-freeze formulations) or methanol (mixed in alcohol), then causes have been ruled out. Then we can safely assume that high anion gap is due to other causes (not related to acidosis).
Dr Vaishalee
Note: For further queries related to kidney problems and comprehensive renal care, talk to a Nephrologist. Click here to Book a Consultation.
Above answer was peer-reviewed by :
Dr. Chakravarthy Mazumdar
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