Tymos and kidney function?

Posted by anewyorker @anewyorker, Aug 25, 2024

Hi everybody,

I'm a 77-yr-old woman who's had osteoporosis for a long time. I started out on Fosamax, had a long (and stupid) medication holiday after about 8 yrs, then went on Prolia, which I took without complication for three years.

Last October I had a compression fracture of the L1 vertebra after tripping over my vacuum and landing on my spine. I began taking Tymlos in January and have basically been OK with it. I do get some side effects after the shot (sometimesheart racing, extra fatigue, and nausea), but I can live with that.

What I"m concerned about is that since going on Tymlos my kidney function has notably decreased, according to the most recent labs. BUN rose to 21 mg/dL from 15 in April, creatinine rose to .95 mg/dL from .84 and eGFR dropped to 62 from 72, both in February. My blood calcium level is 10, within normal limits. Albumin is unchanged and has been stable for years.

Obviously increasing age is a factor--I don't seem to be getting younger--but these changes are remarkable in such a short time. Creatinine is the only waste product that factors into eGFR.

I've searched but can't find anything online about any relationship between Tymlos and kidney function except in terms of elevated calcium levels possibly causing kidney stones, which is not my problem. Does anyone have any information on this?

I'm seeing my endocrinologist next week and of course will bring this up.

Thanks for your thoughts!

Interested in more discussions like this? Go to the Osteoporosis & Bone Health Support Group.

anewyorker | @anewyorker | 4 hours ago

In reply to @kathysueweeks "I’ve been on Tymlos for four months and was shocked to find my GfR went down..." + (show)

@kathysueweeks

It is staggering what we don't know, isn't it? After I posted about this in August 2024, my eGFR declined slightly further in early 2025, coming in at 60 and then 59 (endo and internist, different labs), which isn't terrible given my age but still representd a drop of more than 10 points from Feb 2024 to Feb 2025 (from 72 to 59). My endocrinologist speculated that I was perhaps dehydrated when the blood for the metabolic panel was drawn, since it was late in the morning and I hadn't had anything since the night before, so I've made an effort to drink more water during the day and in fact my eGFR has rebounded in the two latest tests (9/2025 and 11/2025), to 71 (!) from one lab (endo) and 66 from the second lab (internist). BUN and albumin are both stable and well within normal limits (although BUN dropped when I started drinking more, which seems a normal reaction). So who knows?

Good luck to you. I'll be interested in what your endo has to say.

anewyorker | @anewyorker | 4 hours ago

In reply to @kathysueweeks "I’ve been on Tymlos for four months and was shocked to find my GfR went down..." + (show)
@kathysueweeks

Good luck to you. I'll be interested in what your endo has to say.

anewyorker | @anewyorker | 4 hours ago

Oops. Sorry for the duplicate post. Can someone who knows more than I do remove one???

kathysueweeks | @kathysueweeks | 2 hours ago

In reply to @anewyorker "In reply to @kathysueweeks "I’ve been on Tymlos for four months and was shocked to find..." + (show)

@anewyorker

Thank you so much for taking the time to reply in such detail to me. I’ll admit I’ve been a bit scared since I saw how low my GFR is, especially since I can’t consult with my endocrinologist for two more weeks.

I’m happy to hear your numbers went up when better hydrated! That’s so encouraging. And I’ve read on this forum (was that you? 😊) that it’s best to have lab work done when hydrated and also more than two hours after the Tymlos injection ( my labs were within one hour of the injection, fasting, first thing in the morning).

My PCP advised me to really increase my water intake and I’m being re-tested tomorrow. Fingers crossed that it will be higher.

Thank you again for your kind and very helpful response. Wishing you well!