Kidney Biopsy

At Sam's last nephrology appointment, everything was looking great.  His height and weight had moved up percentiles into the 40s.  His electrolyte levels were stable.  His albumin was a little low, but still in the "normal" range.  It had been low a few months ago too.  Our nephrologist ordered a urine test, and this showed protein in the urine.  A LOT of protein.  This took us completely by surprise.

We checked a first morning urine again, hoping it was a fluke.  The massive proteinuria persisted.  We waited almost two weeks to hear back from our nephrologist.  In the mean time, we panicked.  What did this mean?

Cystinosis is a disease of the kidney tubules, which normally reabsorb electrolytes, glucose and small proteins from filtered urine.  It is normal in cystinosis to have leakage of small proteins, but these proteins aren't even detected by normal urine dipsticks.  Sam is losing albumin in his urine, which suggests that the glomeruli are damaged.  The glomerulus is the part of the kidney that filters blood to make urine.  The glomerulus can be damaged by a lot of things.  The most common diseases in kids are minimal change disease and glomerulonephritis.  Other causes include autoimmune diseases, like lupus.  

We hadn't heard of other kids with cystinosis having nephrotic range proteinuria before.  We knew that proteinuria occurred with end stage kidney disease, before transplant time.  Usually the proteinuria is more gradual, however.  Did this mean Sam was going to need a transplant sooner?

It's possible that Sam has something completely unrelated to cystinosis causing the proteinuria.  But it's also possible that the cystine crystals have damaged the glomeruli too.  But why would this happen?  We never miss a dose of Sam's medications.  We are neurotic about that.  We do have some concerns about Procysbi's efficacy compared to Cystagon because Sam did have a really high cystine level several months back.  The effect of Procysbi seems to be more unpredictable depending on what you eat and how strictly you follow rules about eating before and after.

We talked to Dr. Grimm about it via e-mail, and he said that it's possible Sam had sustained enough damage to his kidneys when he was a baby, prior to diagnosis, that now as he grows bigger his remaining functioning nephrons can't compensate.  He may actually be showing signs of "hyperfiltration injury."  He said that sometimes no matter how strict you are with giving medicines on time, the disease just progresses.  It seemed to us that if the cystinosis is progressing, however, then Sam wouldn't be growing so well, and his other electrolytes, like potassium and bicarbonate, would be dropping too.

We heard back from our nephrologist, Dr. Nelson, and discussed the options.  He was baffled by the degree of proteinuria as well, and thought the best thing to figure out what is going on was to get a kidney biopsy.  This meant a short stay in the hospital.  We prepped Sam for it a couple weeks out by telling him he got to have a sleepover at the hospital.  A week before the biopsy he packed a suitcase with pajamas, underwear and movies.

On Friday morning Sam walked in wearing his ninja costume, carrying his suitcase and his stuffed dog, Piratesbandofmisfits (Pirates for short).  First he had to get labs and an IV.  Since he needed to have an empty stomach for the procedure, we had to hydrate him for a few hours before because he drinks a lot of water.  He was pretty nervous about the IV, but once it was in, it didn't seem to bother him.  Ashton's mom watched Lars all day, which was really wonderful so we could both be with Sam.  Around noon Sam was brought back to ultrasound, where he got some versed and ketamine.  Dr. Nelson performed the biopsy and took 4 small core samples.  Usually they do 3, but he wanted to prepare one extra sample to look for cystine crystals in the glomeruli.

The procedure went smoothly without complications.  Sam was taken to the RTU observation unit where he had to lie flat on his back for 6 hours.  We surprised him with a new stuffed animal, a big golden retriever from Ikea that he had been wanting for months.   When Sam saw the new dog he was still waking up from the anesthesia, so he was a little giddy and confused.  "Wait, wait, wait, wait," he repeated with disbelief.  "When did you buy that??"  He named the dog Ivy, after his IV, and then Ivy Scooby-Doo, and eventually he shortened it to just Scooby-Doo.  

Sam spent the rest of the day watching a Scooby-Doo marathon and ordering food from the room service.  He ate an entire personal pizza and serving of french fries for lunch, and a corn dog and fries for dinner.  So healthy.  We had to collect all of his urine to monitor it for significant bleeding.  It started out pretty yellow but by night time it was strawberry colored.  He had some soreness at the biopsy site which got better with tylenol.  He did great overnight and was discharged the next morning.  He was jumping on his hospital bed before he left.  Dr. Nelson told him to avoid rough housing, wrestling and even recess for the next 10 days to make sure he doesn't develop any bleeding at the biopsy site.

So now it's just a waiting game for the pathology results. We are really hoping they find something else on the biopsy, like minimal change disease, that we could just treat with steroids for a while.  If all they see is glomerulosclerosis, or scarring of the glomeruli, then we'll have to accept that it's the cystinosis causing more kidney damage.  The only treatment for that is an ACE inhibitor like enalapril to reduce filtration through the glomeruli, which also decreases how much protein leaks out.

Thanks to everyone who visited, sent messages of support and asked how Sam is doing.  We are fortunate to have such a great community of friends and family.  Now please put your blood types in the comments.