I make about $6,500 donating plasma over 100 times a year, but I don't do it for the money

• Patrick Herdener donates plasma twice a week, every week and makes between $50-$70 per donation.
• That means he typically donates plasma 104 times a year and makes about $6,500 before taxes.
• Herdener said he started donating for money but the spirit of being helpful motivates him now.

This as-told-to essay is based on a conversation with Patrick Herdener, who lives in Tulsa, Oklahoma, and donates plasma twice a week. He receives between $50-$70 per donation, which Insider verified with documentation. The conversation has been edited for length and clarity.

To be honest, when I first started donating plasma, the main thing that motivated me was money. I was in my mid-20s, unemployed, and had rent to pay.

My best friend at the time told me about plasma donation, where I could earn money by letting a machine filter plasma out of my blood. Back then I think the pay was around $30 a session. I would go just enough to pay the bills, since I was single and had no family.

Now though, I'm a lot more serious about it. I go twice a week, usually on Wednesday and Friday, every week of the year.

These days I come home with between $55 and $70 for each session. On Wednesdays, they pay me $55 and on Fridays, it's $70. It adds up to around $6,500 per year before taxes.

This isn't my main income though. I mostly use this to buy my wife and kids birthday gifts and Christmas presents. And to replace parts on my mountain bike. I break a lot of parts.

I started donating more often when I learned where my plasma was going. My plasma donation center, run by CSL Plasma, put up a sign listing the illnesses and disorders that plasma can help treat, like hemophilia or immune deficiency.

Around two to three years ago, they put up another sign. Every month, it shows a new photo of someone who receives treatment for one of those disorders. It's actually kind of nice — makes it a bit more personal.

I have been donating twice a week for 13 years. The only time I've paused during that period is when the machine filtering my blood broke during a session.

The bowl holding my blood was full, and it had just started to spin the plasma, when suddenly it broke. I lost a bowlful of blood immediately — not just my plasma, but the red blood cells, as well.

I was fine. I still went to work and rode my bike home afterwards. They still gave me a full payout, too.

But I had to wait 58 days to replenish that blood I lost. You can't donate if you're short on blood. That could send you to the emergency room if you tried.

Other than that one incident, my streak has been unbroken.

The nurses use an 18-gauge needle to draw my blood. There's only one vein in my arm big enough for that size of needle. That's why I switch arms, so my scar tissue doesn't get too thick. I also use a vitamin E gel to help my skin heal and reduce scarring.

The pain usually isn't too bad. It depends on the person sticking you. With some people, the pain is no worse than when you donate blood. With others, you don't feel a thing.

The process normally takes 49-55 minutes. One lucky day, it only took me 35 minutes, but that was a one-off. I can't replicate it no matter what I change.

To help keep the process quick, I stay away from most pork products and only eat cheese in moderation. Those foods raise the fat content in my blood, which can clog the filter in the machine.

When the filter gets clogged, a process that normally takes me 49 minutes turns into 2 hours. By the end, my arm aches from my elbow to my fingers.

I also drink a gallon of water daily. Staying hydrated is important so you don't get light-headed.

I'd encourage others to donate plasma if they can. It's only an hour out of your day, and it really does help people. You might even find an interesting conversation with fellow donors or the nurses while you're at it.