Understanding Acid-Base Disorders: Metabolic Acidosis

Pentec Health CEO Joe Cosgrove has addressed before the topic of dialysis in several occasions; however, and given the variety of health issues related to renal failure, it is also important to discuss and clarify the doubts people may have about other renal pathologies such as acid-base disorders.

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Image courtesy of Steve Davis at Flickr.com

Since acid-base disorders entails the deep study of kidneys, and every case depends on the patient, if one were to fully understand this topic, one would need to go through all the formulas in order to completely get the full picture of a given case, nevertheless, there is a way for readers to understand what is this thing commonly referred to as “compensation”—or renal compensation in an acid-base disorder, for this matter—, and furthermore understand what is going on under these circumstances. To understand compensation, it is advisable to take a few steps back in order to see a depiction of what is happening in the blood when it has a lot of acid as in metabolic acidosis, for instance.

Actually, acid-base disorders comprise four scenarios: metabolic acidosis, metabolic alkalosis, respiratory acidosis and respiratory alkalosis, however, and since each scenario demands a succinct study, this article focuses on metabolic acidosis. In a metabolic acidosis, what normally happens is that patients experience a drop in their serum bicarbonate, and what physicians strive to assess is how far the patients’ CO2 will fall, since it is expected to drop. This might sound very technical, so for people to understand this much easier, simply put, metabolic acidosis refers the condition where there is too much acid in the body fluids—which causes the bicarbonate drop mentioned before—; and, as in every pathology, there are some possible causes that can ultimately result in metabolic acidosis, specially three main categories: either patients have a lot of acid being produced in the body: patients suffering from DKA (Diabetic Ketoacidosis) are more likely to suffer from metabolic acidosis given their increased and extremely high blood sugar levels and ketones production which causes bicarbonate to go down; or patients experience a decreased acid excretion: patients who suffer from kidney failure cannot filter all the waste products and byproducts causing the acid to stay in the body and consequently rise its levels; and the another cause is the loss of bicarbonate: people can lose bicarbonate from diarrhea, for instance, and as consequence the acid stays in the body. In general, metabolic acidosis causes the arterial blood gases values to exceed their normal levels while the body struggles to compensate: the respiratory system sees that there is too much acid in the body and starts to breathe more rapidly so that the CO2 can be expelled out of the body in hopes of raising the blood pH back to normal, and consequently increase the bicarbonate level.

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Image courtesy of Laura Whitehead at Flickr.com

Patients suffering from severe metabolic acidosis are commonly seen doing deep rapid breaths in order to expel all the CO2 (which is an acid) so that the blood pH can get to its normal values. Other causes that can result in metabolic acidosis can be found aside the three mentioned before. For example, aspirin toxicity has been correlated with metabolic acidosis: patients who have taken a lot of aspirin accidentally will experience a dramatic rise in their acid levels once the body has absorbed it. This will likely cause them to hyperventilate since, as explained before, the respiratory system will try to get rid of the excess of acid by expelling CO2 (causing, furthermore, respiratory alkalosis). Another cause has been linked to carbohydrates not being properly metabolized: there are plenty of metabolic issues and it is often seen the case where patients struggle to metabolize carbohydrates which in turn prevents the body to break down pyruvic acids due to the lack of oxygen. Not being able to break down the pyruvic acid, the body turns it into lactic acid, which almost shuts down the body and causes the bicarbonate levels to drop.

A third cause is inherently related to kidney failure: the kidneys, which are responsible for filtering the waste out of the body, fail to do so causing the body to store waste and acids in the blood. As readers might have already imagined, having increased acid levels causes the bicarbonate levels to fall. Actually, every single thing that causes either a loss of bicarbonate or alkaline fluids, or retention of acids, might result in metabolic acidosis, moreover, even a wrong diet can be directly linked with this pathology: an intake of high-fat diet increases the likelihood of increasing the waste, acids, and ketones in the body. Since the body is not a perfect machine and sometimes fail, one can certainly assert that an excess of fat, or any excess, results in something bad for the body: having a good and healthy lifestyle will surely help patients to keep their kidneys functioning for much longer.

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