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Candice was a high school student on the track team andtraining for her upcoming cross-country meet. She woke up brightand early to complete a 10-mile run. Her workout ended up takingher a little longer than usual and she was sweatingprofusely.

As Candice cooled down from her run, Candice’s Mom yelled fromthe kitchen, “Candice, your breakfast is ready! Come eat. You lookso pale!”

“Oh, really? I’m starving; maybe that’s why? What did youmake?”

“Your favorite... eggs benedict with a side of toast andorange juice. So, how was your run? It seemed like it took youlonger than usual.”

“I felt a little more tired than I usually do, but I stayedstrong. Nothing to worry about,” Candice assured her.

“You need to stay healthy for the invitational meet onSaturday. As you well know, your performance on Saturday willdetermine your eligibility for states. Maybe you should rescheduleyour date with ... ”

“Mom! I’ll be fine. Trust me,” Candice exclaimed.

Candice finished her breakfast and, while taking a hot shower,felt a cramp developing in her left leg. Not thinking too muchabout it she took a naproxen tablet, rubbed the cramp and proceededon with her day. After studying for about an hour she realized thatthe naproxen wasn’t working because her muscles still felt sore.Oh, no…this is bad timing. I have a date with Phil tonight, Candicethought. So, she took another naproxen tablet.

Half an hour later, Candice felt dizzy and lightheaded and herskin began to feel clammy, which she believed was due to thehumidity. She felt her heart race and tried to calm herself, butthe leg cramps started coming back. Although Candice prided herselfon a high threshold for pain, she finally told her mom thatsomething was wrong and that she needed to go to thehospital.

List the problems that Candice experienced.

Can you see any common features in Candice’s problems?

Do you think Candice overreacted by saying she wanted to go tothe hospital?

Do you have a prognosis for Candice’s problems?

“Candice, honey, I think you’re overreacting. How about I takeyou to the urgent care?”

“Fine, Mom!”

The nurse at the urgent care took Candice’s history andphysical.

History and Physical Report

Patient Candice Pearson

History

Physical

Chief complaint: Lightheadedness, fatigue, muscle cramps

Age: 17

Past medical history: Polycystic ovarian syndrome [Treatment →150 mg spironolactone daily]

Height: 5´6˝

Past surgical history: Wisdom teeth removed (3 monthsago)

Weight: 130 lbs.

Drug allergies: Penicillin

Temperature: 97.8°

Heart rate: 110 beats/min (normal: 60–100)

Blood pressure: 98/56 (normal: 120/80)

Pinch skin: skin bounces back slowly

History and Physical Report Patient: Candice Pearson HistoryPhysical Chief complaint: Lightheadedness, fatigue, muscle crampsPast medical history: Polycystic ovarian syndrome [Treatment → 150mg spironolactone daily] Past surgical history: Wisdom teethremoved (3 months ago) Drug allergies: Penicillin Age: 17 Height:5´6˝ Weight: 130 lbs. Temperature: 97.8° Heart rate: 110 beats/min(normal: 60–100) Blood pressure: 98/56 (normal: 120/80) Pinch skin:skin bounces back slowly.

“Wow, Mom, my heart rate’s high; it’s usually around60.”

“Maybe you’re just nervous, honey.”

The nurse decided that Candice was probably experiencingdehydration from her run. She recommended rest and drinking plentyof fluids like water and Gatorade.

What new information has been revealed?

Which of Candice’s problems could have been caused bydehydration?

Which problems could have been caused by something other thandehydration?

Where is blood pressure monitored in your body?

Which part of the autonomic nervous system is activated whenblood pressure is low?

What is the effect of this part of the autonomic nervoussystem on heart rate and stroke volume?

If Candice is correct and her resting heart rate is usuallyaround 60, why is her blood pressure low?

Would you like to change or modify your prognosis?

After driving home from urgent care, Candice began to getready for her big date night with Phil. She had a new dress pickedout and invited her friend, Maria, over to help with her hair andmakeup.

“You look great! Phil’s going to be blown away,” Mariaencouraged her friend.

“I hope so. Though, I’m still a little nervous. I think I’mgoing to take a couple of my prescription pills. I missed my dosethis morning.”

“Are you sure?” Maria asked.

“Yeah, it’s alright. And I think it makes me look and feelbetter,” Candice said reassuringly.

Phil arrived to pick up Candice for the date. Ever thegentleman, he had picked out a nice romantic Italian restaurant.Candice ordered spaghetti marinara and Phil ordered fettuccinealfredo.

They finished dinner and headed to the movies. Candice was nota fan of scary movies but agreed because Phil wanted to see it.About halfway through the movie, she started feeling a littlelight-headed and her heart started racing. It’s probably the bloodin the scary movie messing with me, she thought. She tried to calmherself, not wanting to ruin their first date.

She turned to Phil, “Sorry, but I think something’s wrong! Ifeel sick!” Phil guided her out of the movie theater, where shethen collapsed and complained that her chest felt really tight.Candice thought to herself, Oh no, I think I’m going to be sick.How embarrassing! There isn’t going to be a second date.

Phil called 911 and an ambulance quickly arrived.

Make a list of any new problems Candice is experiencing. Doany of Candice’s new problems correlate with your previousprognosis?

Why is Candice having chest tightness?

How does the nurse’s diagnosis of dehydration affect the bloodpressure and circulation?

What did Candice eat for dinner? How could her food choice atdinner cause these problems?

List tests that the doctors should perform at thehospital.

Candice’s mother arrived at the hospital as the EMT movedCandice into the emergency room where she was placed under the careof a new resident. The resident began to check her vitals and tooka report of Candice’s problems while her mother anxiously pacedback and forth. He then listened to her breathing sounds, whichappeared normal. Next, the resident ordered an ECG, chest x-ray, CTbrain scan, and metabolic profile of Candice’s blood work. In themeantime, he asked about her previous medical history, anymedication she was currently on, and what she ate recently.

“I just ate spaghetti marinara. I am on spironolactone becauseI have polycystic ovarian syndrome. I took two tablets right beforedinner because I forgot to take it this morning. After my runearlier in the day, I had intense muscle cramps so I ended uptaking two naproxen tablets. I was starting to feel better in theafternoon so I thought I would be okay to go on my date.”

The resident asked, “How much water did you drinktoday?”

“Not much,” Candice admitted ashamedly.

“Well, you should know spironolactone is a diuretic. Yourphysician should have told you to drink plenty of water when youare taking this drug. It works as an aldosterone receptorantagonist in the cells of the distal tubule in your kidney, whichmeans that you will lose a lot of water. You need to stayhydrated,” warned the resident.

The resident then left to pick up the test results.

Fill in the table to predict the results of the initialtests.

Tests

Results

Heart rate

EKG

Chest x-ray

CT scan

Blood K+

Blood Na+

Aldosterone is responsible for controlling blood sodium andpotassium levels. What type of hormone is aldosterone and whichcells secrete it?

The resident returned with the tests results: the CT brainscan was normal, the EKG showed an elevated heart rate witharrhythmia, the chest x-ray was normal, and the blood work showedan electrolyte imbalance.

Here is a partial list of Candice’s blood work:

Test

Candice

Normal

Glucose, Serum (mg/dL)

82

65-99

Uric Acid, Serum (mg/dL)

4.2

2.5-7.1

Creatinine, Serum (mg/dL)

1.2

0.57-1.00

Sodium, Serum (mEq/L)

133

134-144

Potassium, Serum (mEq/L)

7.0

3.5-5.2

Chloride, Serum (mEq/L)

103

97-108

Calcium, Serum (mg/dL)

9.5

8.7-10.2

20. What abnormal values are evident in Candice’s bloodwork?

21. What could cause an elevated heart rate?

22. What minerals do tomatoes have in highconcentrations?

23. Could the tomatoes have had an effect on the level of thatmineral in Candice’s blood?

24. Use the Nernst equation (below) to calculate theequilibrium potential for potassium in a normal patient and inCandice; assume [K]in is 150 mEq/L in Candice and in normalpatients, and [K]out is 4 mEq/L in normal patients.

E K+ (millivolts) = 61 log10 ([K+ ] out /[K+ ] in)

25. If the resting membrane potential exhibits the same changeas the equilibrium potential for potassium, predict how Candice’sion imbalance will affect a cell’s resting membrane potential;would Candice’s resting membrane potential be hyperpolarized ordepolarized?

The resident and attending returned and talked to Candice andher mother.

“Candice, you are suffering from hyperkalemia, which means youhave more potassium in your blood than normal. Two things happenedto you today to create the perfect storm. First, you ate a mealhigh in potassium and second you took a high dose ofspironolactone. The drug blocks the action of a hormone in yourbody called aldosterone, which works to rid your body of excesspotassium, exchanging it for sodium. Decreased aldosterone activitymeans the level of potassium in your blood increased while thelevel of sodium decreased. Also, the loss of sodium in your urinecauses you to also lose water.”

“So I guess that’s why it’s a diuretic,” interruptedCandice.

“Exactly. The elevated potassium levels in the fluid aroundyour cells is responsible for your heart arrhythmia, high heartrate, and muscle cramps. I recommend staying away frompotassium-rich foods like bananas and tomatoes.”

“Usually I do; I only eat apples and oranges.”

“I also suggest taking acetaminophen instead of NSAIDs, likenaproxen, as it is thought that there may be some drug interactionthat further increases hyperkalemia. You have to be careful whatyou eat; your body is losing a lot of water and sodium so hydrationis key when you are on spironolactone. I recommend that your dietconsists of low potassium and high sodium meals as well as a lot ofwater or Gatorade, especially while you are training. This couldhave been a lot worse if you hadn’t come in for treatment. Arethere any concerns you would like to address?” asked theresident.

“No. Thank you so much! I’ll try to be more careful in thefuture,” said Candice.

Where is the pacemaker for the heart?

How could membrane depolarization created by elevated bloodpotassium level cause an increase in Candice’s heart rate?

How could the membrane depolarization created by the elevatedblood potassium level cause arrhythmias?

How could the membrane depolarization created by the elevatedblood potassium level cause muscle cramping?