The Ninety-Nine Percent

The machine beside Uncle Ravi made a sound like a slow heartbeat, and a tube the color of cranberry juice ran out of his arm, curled through a box, and ran back in.

"So it's cleaning your blood," Soren said.

"Doing my kidneys' job," Uncle Ravi said. "They quit a few years back. This thing works four hours, three days a week."

Maya was watching the tube. "Four hours, three days a week. That's twelve hours."

"Give or take."

"That's not very much," she said.

The nurse hanging a fresh bag laughed. "Tell that to the machine. It's a very hard twelve hours." She tapped the box. "A healthy pair of kidneys does this all day, every day, no breaks. Filters about a hundred and eighty liters a day."

Soren stopped. "A hundred and eighty liters."

"Mm-hm." She moved on to the next chair.

Soren already had the notebook open on his knee. His pen moved. "How much blood does a person even have?"

"Like five liters," Maya said. "I read it on the poster over there." She pointed to a chart of a body with all its plumbing drawn in.

"Five liters," Soren said. "And the kidneys push a hundred and eighty liters through in a day."

Maya went quiet. Then, "That's the same blood. Over and over."

"How many overs?"

She did it out loud, slow. "A hundred and eighty divided by five. Thirty-six." She frowned. "No. It's not all blood they filter. Some of it's just the watery part." She looked at Uncle Ravi. "Right?"

"The plasma, yeah," he said. "They pull the water out and sort through it."

"Then it's more overs," Maya said. "Because the watery part is less than the whole. Your whole blood goes past those kidneys like sixty times a day."

Soren's pen stopped. "Sixty times. Your entire blood volume. Every day. That's more than twice an hour."

"While you sleep," Maya said. "While you're doing nothing. Sixty laps."

They both looked at Uncle Ravi's arm, at the cranberry tube going out and coming back.

"Okay but here's the thing I don't get," Soren said. "A hundred and eighty liters of water comes out of your blood. Where does it go? You don't pee a hundred and eighty liters. You'd be a fountain."

"About a liter and a half," Uncle Ravi said. "When I still made any. That's what comes out."

Maya sat forward. "A liter and a half. Out of a hundred and eighty."

"So where's the rest," Soren said.

"It goes back in," Maya said slowly. "It has to. There's nowhere else. They take out a hundred and eighty liters of water and put back a hundred and seventy-eight and a half."

Soren was doing the division. "That's ninety-nine percent. They take it all out and then put ninety-nine percent of it back."

"That's insane," Maya said, and she said it like it was the best thing she had ever heard. "Why would you take it out just to put it back?"

Soren looked up from the notebook. "Because you're not doing it for the water. You're doing it for what's in the water."

Maya stared at him.

"Think about it," he said, faster now. "You've got salt in there. And potassium and all the stuff on the poster. And it has to be exactly right, doesn't it? Uncle Ravi, doesn't it have to be exactly right?"

"Too much potassium stops your heart," Uncle Ravi said, quiet. "That's the honest answer. That's why I come here."

The machine kept its slow heartbeat.

"So you can't just leave the blood alone," Soren said. "You can't just trust it to be right. Every drop of water in you, sixty times a day, gets pulled out and checked and only the exact right amount of everything goes back. The rest, the tiny bit that's wrong, that's the liter and a half."

"The pee is the mistakes," Maya said.

"The pee is the leftover," Soren said. "The one percent you didn't want back."

Maya stood up. She walked to the poster and put her face close to it, to the two dark bean shapes tucked under the ribs. "Everybody has these," she said. "Everybody in this room. Right now. Not knowing. Doing sixty laps."

"Mine aren't," Uncle Ravi said. He wasn't sad about it. He was watching them like they were figuring out something he'd stopped being able to feel amazed at. "That's why I get to sit next to the machine that does it for me. And it's the size of a dishwasher. And it's not as good."

"Not as good as the beans," Maya said.

"Not close," he said.

Soren looked at the dishwasher-sized machine, and then at the poster, at the two shapes each no bigger than a fist.

"They fit under your ribs," he said. "Both of them. And they do more sorting in one hour than that whole machine does in four."

"And nobody teaches them," Maya said. "They just do it. From before you're born. They just start."

She pressed her thumb against her own side, low, under the last rib, feeling for something she would never actually feel.

"It's happening right now," she said. "In me. While I'm standing here being confused about it."

The machine beeped. The nurse came back and checked a number and nodded and went away again.

Soren wrote one line and turned the notebook so Maya could see it. It said: sixty times, every day, and you never once feel it happen.

Maya read it. Then she put her hand flat against her uncle's forearm, above the tube, where the blood was going out to be sorted by a machine because the beans had stopped, and she felt it come back in warm.