A lab test for pH done as part of a urinalysis or the more invasive arterial blood gas measurements taken from arterial blood can provide very accurate and high precision measurements of pH. However, these measurements may not be meaningful to us as cluster headache sufferers as a single datum unless well out of the normal range. Moreover, a single pH measurement does not take into account the daily fluctuations in arterial pH that occur and it gives no trend information unless repeated on a daily basis at the same time each day.
My motivation for measuring my saliva pH as an analog of arterial pH was to determine if a relationship existed between changes in arterial pH and changes in the trends of my cluster headache patterns, i.e., was my saliva pH trending lower or higher as I went into a high cycle of cluster headaches.
As you'll see in the chart below there was a direct correlation between an elevated saliva pH following oxygen therapy at flow rates that supported hyperventilation. You can also see that each of my cluster headaches was associated with a lower saliva pH than the daily average for that day. On Day 14 I had the lowest average daily pH. I was also awaken twice with cluster headaches that night so this was an indication that when my daily average pH trended lower (more acidic), the frequency of my cluster headaches began to increase.
Granted, the trend information is still anecdotal, but it's been consistent enough for me over the last year to start the regimen of calcium citrate tablets washed down with lemonade or margarita mix high in citric acid whenever I start into a high cycle.
In fact, this same regimen reduced the frequency of my attacks even further during a low cycle. From the first of July through the 25th of August, I had a grand total of 8 cluster headaches. All were associated with days where I either skipped the regimen or ran out of margarita mix. I also had 8 pain free airline flights during that time frame and 4 of them were over 5 hours in duration.
The easiest, least inexpensive and most non-invasive way to check arterial pH is to measure the pH of saliva as an analog to arterial pH using pH test strips. Although it's not the same, the pH of saliva parallels arterial pH with a 10 to 15 minute time lag.
Taking three measurements of saliva pH using test strips at the same time each day (morning before breakfast, noon before lunch, and evening prior to bed time) and averaging them provided much more meaningful indications of arterial pH trends than any single lab test.
I use the pH test trips from pH ion at the following link:
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They measure pH in 0.25 increments and they're easy to read provided you use the same light source. There are also 90 strips for $15 plus shipping so each pH measurement costs 17 cents.
If you record a week's worth of daily pH measurements taken three times a day when out of cycle if episodic, or during a low cycle if chronic, you'll have a good reference value to measure against when your cluster headache patterns change for the worst.
The green line on following chart represents two weeks of daily average saliva pH measurements.
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The red dots and lines represent pH measurements taken as soon as I woke up with a cluster headache and the blue dots the pH measurement taken 5 minutes after I aborted the cluster headache with oxygen at flow rates that support hyperventilation. All of these aborts took 4 to 5 minutes or less.
I was in a low cycle at the time with 10 attacks over the two week period. With the exception of Day 14 when I had two attacks, all the rest of the attacks came at the rate of one a night while sleeping and were easily aborted with high flow rate oxygen therapy. As you can see the saliva pH is just about back to the daily average or slightly above when measured at least 5 minutes after the abort with oxygen therapy.
I also started using a finger pulse oximeter on Day 7. My oxygen saturation levels were clearly low when measured as soon as I woke up with an attack, but they were still fully saturated 5 minutes after completing oxygen therapy and the abort.
I've no doubt that my CO2 levels were well above normal when I awoke with a cluster headache. That would correlate inversely with the lower pH as excess arterial CO2 increases the acid content of arterial blood.
I hope this helps clarify the relationship I detected between a low arterial pH measured with saliva pH and an increase in the frequency and or intensity of my cluster headaches. This was also my rationale for using the regimen of calcium citrate and lemonade or margarita mix.
There is actually good science behind this regimen if you want to wade through the attached British Journal of Anesthesia article on the results of a clinical trial titled, "An oral sodium citrate-citric acid non-particulate buffer in humans."
In keeping with the standard disclaimer, the above discussion of a low arterial pH and taking calcium citrate to elevate it was provided for information purposes only. Discuss the use of calcium citrate with your PCP or neurologist as it can interfere with other medications.
Take care,
V/R, Batch