Bet You Never Heard of This Kind of Duplex 

I’ve been writing this blog for over a decade and am continually amazed that new topics keep coming up. There is so much to chronic kidney disease. Today’s new topic is duplex kidneys. You read that correctly: not duplex housing units, but duplex kidneys. 

Everyone know what duplex means? Haha, you’re so clever. Indeed, we are turning to my favorite dictionary since college over 50 years ago. The Merriam-Webster Dictionary tells us it means, 

“1a: having two principal elements or parts: DOUBLE, TWOFOLD 

b: having two complementary polynucleotide strands of DNA or of DNA and RNA 

2: allowing telecommunication in opposite directions simultaneously “ 

This is the adjective (describes a noun or pronoun) definition of the word. There’s also a noun (person, place, thing, or idea) definition, and a verb (action word) definition. In our case, we need the adjective definition because we are describing the kidney. Specifically, we need definition 1a. 

I know, I know, enough with the English lesson and on to the actual duplex kidney. A new source, Denver Urology Associates, explains duplex kidneys: 

“Duplex kidney is the duplication of the ureter tube, which drains urine from the kidney to the bladder. The condition results in two tubes rather than the normal single ureter tube for each kidney. 

Duplex kidney (also known as duplicated collection system) occurs in about 1 percent of children and usually requires no medical treatment. Medical concerns relate to obstruction of urine flow or urine flowing back into the kidney. 

The function of the kidneys is to filter waste from the blood and convert it to urine to be dispelled from the body. The urine travels from the kidney to the bladder via the ureter tube. The bladder expels urine through the urethra tube, which emerges at the tip of the penis in boys and at the upper region of the vagina in girls. 

In the duplex kidney condition, the kidney forms in two, duplicate parts with separate ureter tubes, as well as a separate blood supply. In about half of duplex kidney cases, both kidneys are affected with the duplicate ureter and blood supply. 

These double ureter tubes may join together in a ‘y’ shape before they reach the bladder and combine their delivery of urine. Or in other instances, each duplicate ureter will drain into the bladder via its own attachment. 

In either case, the result is the same — and generally the same as in a normal kidney with only one ureter.” 

Considering one of the babies in my daughter’s social circle has been having kidney problems, I wondered what the symptoms of duplex kidneys are. I turned to the UK’s Top Doctors for answers: 

“Duplex kidneys and duplicated ureters that drain directly into the bladder rarely cause any symptoms. 

However, if there is a complete second ureter, this often functions poorly and can be connected to a number of problems: 

Urinary tract infections (UTIs) – problems in urine drainage make it easier for bacteria to enter the urine and travel to the bladder. Under certain conditions, infections can even spread up to the kidneys. 

Ureterocele – the end of the ureter doesn’t develop properly, causing urine to be obstructed and become backed up. The ureter begins to swell and balloon where it enters the bladder and the length of the tube may become swollen as more urine backs up along it. 

Vesicoureteral reflux – urine is able to flow back through the ureter, sometimes even as far as the kidney. This may be because of an abnormal connection between the ureter and the bladder or as a result of a ureterocele. 

Hydronephrosis – the ureter and kidney swell due to urine being backed up. This may be due an abnormal connection between the ureter and the bladder or as a result of a ureterocele, and can lead to kidney damage. 

Ectopic ureter – the ureter does not connect to the bladder, instead being blocked or leaking into another part of the body. This can lead to vesicoureteral reflux, hydronephrosis, swelling, and incontinence.” 

Logically, the next question would be, “How are duplex kidneys diagnosed?” Children’s Hospital in Colorado had the answer: 

“A duplex kidney is most commonly diagnosed by using an ultrasound scan. This is a simple test that looks at the kidney and it is not painful. Sometimes it is necessary to do additional tests, which can include a voiding cystourethrogram (VCUG), where a catheter is placed into the bladder and X-rays are taken as the bladder is filled. Another test used to diagnose this condition is a renogram, where the function of the kidney is evaluated.” 

Now here’s a surprise. This is what you do if your baby has a duplex kidney. Doctor of Internal Medicine, Anthony L. Komaroff, tells us, 

“No treatment is needed. There is no harm to the kidney, though some people with duplex kidneys are more prone to urinary infections, reflux and blockages of the urinary tract.” 

I’m not a doctor, but that didn’t sound right to me, so I looked at site after site to check on it. It turns out that while a duplex kidney may not need treatment, the problems they may cause do need treatment. That made more sense to me, especially as the baby I mentioned is being treated for vesicoureteral reflux. I have no idea if she has duplex kidneys, but it seems vesicoureteral reflux does need to be treated. 

The Children’s Hospital of Philadelphia put this into perspective for us: 

“Duplex kidneys are a normal variant, meaning that they occur commonly enough in healthy children to be considered normal. They occur in 1 percent of the population, and most cause no medical problems and will require no treatment.” 

Oh, that means if the baby in question’s vesicoureteral reflux was caused by duplex kidneys, she does NOT have chronic kidney disease. I know one mama who’s going to be very happy when she reads today’s blog. 

Enjoy your holidays and be safe! Remember that any of the SlowItDownCKD book series would be a really good gift to give someone with CKD, their families and their friends. Talking about friends, one suggested that your primary care doctor could learn a lot about CKD from these books, too. By the way, that’s one book a year since 2010. Love, peace, and joy to all of you. 

Until next week, 

Keep living your life!