What causes extreme weakness with low carbon dioxide?

Hello doctor,

I am experiencing episodes of extreme weakness, lethargy, and tiredness. I feel unable to get out of bed, and I find myself going to the bathroom often at night. Two years ago, I had an ECG-proven ventricular tachycardia after an episode that lasted for several days. I have had lab tests done close to two episodes. A month ago, my carbon dioxide levels were slightly low at 19, and there was trace blood in my urine. The USG (Urine Specific Gravity) reading was 1.005, and the urine pH was 7.

Recently, this month, my second lab results showed mildly low bicarbonate levels. The current medications I am taking include Methotrexate, Mobic, Metoprolol, Vitamin D, and Folic acid. I have undergone lab tests for blood and urinalysis.

Kindly help.

Hi doctor,

Thank you for answering so quickly with some ideas. I would be interested in exploring how to rule out renal acidosis. If you make recommendations on which additional labs to collect, I will try to get them during the next episode if I can get to my general practitioner. I have taken Methotrexate for the past 10 years, but recently halved my dose of it. This issue with the tired spells began four years back. I have a history of dermatomyositis and have recently weaned off Prednisone, which I hoped would have fixed the issue, but I have had two episodes since stopping the Prednisone.

During the ventricular tachycardia (VT) episode in the hospital, my

1. Blood Urea Nitrogen (BUN) and Creatinine levels were low at 11.2 (range 12-20).
2. Chloride (CL) level was high at 110 (range 98-107).
3. Potassium (K) level was within the normal range at 4 (range 3.5-4.1).

On the second day of admission in the Critical Care Unit (CCU) on intravenous (IV) therapy, my

1. BUN and Creatinine levels were high at 21.7.
2. Chloride (Cl) level remained high at 111.
3. The carbon dioxide (CO2) level was low (22-32).
4. Potassium (K) level was normal at 3.7 (range 3.5-5.1).

I was discharged on Metoprolol, and it seemed to help with the episodes, but I still occasionally experience them. I am considering seeking a kidney consultation after a suggestion from a nurse friend.

Kindly suggest.

Hi doctor,

Thank you for the reply.

Ok, so I read up on this, and it says autoimmune disorders can cause distal renal tubular acidosis (RTA). I have had low complement in the past, so my dermatomyositis is more of the overlap variety of connective tissue disorder. So, I think ruling out this RTA might be a good idea since it seems to be very treatable. I am going to my general practitioner this week to talk to her about this, and I guess my main questions are:

1. Can this manifest in discrete episodes or extreme weakness verging on paralysis?
2. Do you know of cases where this was induced by medications or diet?
3. Do you know why my osmolality is high if I drink plenty of water and have no diarrhea or vomiting? Shouldn't my ADH (antidiuretic hormone) also be high if my osmolality is that high?
4. My bicarbonate is not super low, but only mildly low. Is that enough to convince a doctor to try to test for RTA? As I understand it, when my bicarbonate is low, my urine pH should adjust to it, so is seven a bit high to have at the same time as low bicarbonate?
5. My electrocardiogram, in addition to ventricular tachycardia, has had t-wave inversions, left axis deviation, and right conduction delays. Could that be caused by something like this?

Hello doctor,

Thank you for your prompt reply.

My last EKG (electrocardiogram) was four years back, and I still have myopathy, but it showed up as mild non-irritable myopathy in my proximal muscles and also my tibia muscle. I was told it could be because of a longstanding disease. Thank you for the answers. I was going to ask the doctor if maybe my ADH (antidiuretic hormone) could be low because of long-term steroid use and adrenal insufficiency to see if that would be playing a role. I drink 100 ounces of water a day plus a sports drink, so it is really frustrating to be constantly told I am not drinking enough. My urine pH (potential of hydrogen) has been 7.

1. Is the urine pH of 7 not neutral?
2. Is it that it should be lower in the context of low bicarbonate?
3. My bicarbonate is not always low; it only seems to be low during these attacks. Could you explain a little bit about why you think it is good to rule out distal RTA (distal renal tubular acidosis)?

I appreciate your time. Sorry, I meant EMG (electromyography) above in the previous query.

Hello doctor,

Thank you for the insight.

I understand a little better now.

1. So, you are saying maybe if my osmolality went up a little more, the ADH would punch the gas eventually, basically?
2. One last question on RTA, could it make me dehydrated?

My time limit is just about up. I will run these tests with my doctor and let you know at a later date if they yield any useful information on my case.

Thank you for your time.