Blood Work “Chris. Michelle. You go on... I’ll catch up in a minute.”Mary hid he
ID: 3518556 • Letter: B
Question
Blood Work
“Chris. Michelle. You go on... I’ll catch up in a minute.”Mary hid her fear as she struggled to catch her breath. She had been so excited to go hiking with her children. Chris and Michelle were both home on fall break, and Mary had been looking forward to the family time. But she felt like she was hyperventilating, and now her chest was starting to hurt.
“What, we’ve finally outlasted you on the trails?” Chris joked as he looked over his shoulder. “Mom, are you ok? You look awful.”
“Don’t panic, but I think I need to go to the hospital.”
“Michelle! Go get the car!” Chris yelled ahead.
“Please don’t panic—I just want to get it checked out.”
“Michelle!”
After what seemed like an eternity, they arrived at the hospital. As Chris and Michelle helped their mother into the waiting room, the ER attendant noticed them and ushered the family into a small room. Dr. Rosen promptly took Mary’s medical history and ordered an EKG, chest x-ray, blood tests, and urinalysis. The tests were completed in short order, and about an hour later, Dr. Rosen appeared in the exam room. “Ihave some good news, and a little bad news. The good news is...”
“Dr. Rosen to the ER, Code Blue. Stat!” said the voice on the PA.
“Sorry, that’s my cue. But don’t worry, you’ll be fine...once we get you offof the Topamax®. This might takea while, so I’m leaving your chart. I hope I’ll be back to review the test results with you, but it might besomeone else,” said the doctor as the door swung shut.
“Mom, isn’t Topamax your migraine medicine?” asked Michelle.
“Yes. It was originally designed as an epilepsy treatment, but I take it to prevent those migraines that used toput me in bed all day. How could it be causing this?” Mary wondered out loud.
Chris broke the tension, saying, “These are your records, right? Let’s see what we can figure out.” He flippedopen her chart. On the top of the pile were Mary’s blood test results:
Normal range
Mary’s results*
Hemoglobin (g/dL)
12.0–15.0
12.8
Hematocrit (%)
36–44
37.5
Creatine kinase cardiac isozyme
0–3.9%
1
Creatine kinase MM isozyme
96–100%
99
Creatinine
0.5–1.4
0.9
pH
7.35–7.45
7.31
pCO2
(mmHg)
38–52
18.1
pCO2
(mM)
20–27
9.5
pO2
(mmHg)
70–100
121.0
HCO
3
-
(mM)
19–25
8.9
Glucose (mg/dL)
90–140
112
Mary has an acid-base disturbance that is being compensated for with another body system. Identify the specific type of disturbance and trace out the physiological pathway responsible for the compensating action.
Explanation / Answer
The disturbance would be the low bicarbonate in Mary’s blood, the Topamax is the physiological reason behind the low bicarbonate.
Compensated by blowing off CO2 with more rapid than normal breathing:
H2CO3---->H2O + CO2 (gas)