Updated August 04, 2014.

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Polycystic kidney disease (PKD) is characterized by presence or growth of numerous cysts in the kidneys. Unlike simple cysts discussed here, PKD is not a benign disease, and a large fraction of patients risk advancing to the point where their kidneys fail completely and they need dialysis or a kidney transplant. Lets discuss the available treatment options for PKD in this article. How PKD occurs and who is at risk is covered here.

Who is likely to develop kidney failure and its diagnosis is covered here. 

ROLE OF ADH

As much as I want to keep this article simple for the average reader, let me make a brief detour to the role of a hormone called ADH, or the Anti Diuretic Hormone (also known as Vasopressin) that is produced by the pituitary gland. This is a hormone that acts on the kidney and makes it retain water. It is what makes the urine look dark and concentrated when you have not had enough water to drink, or spent a day outside in the hot sun. If it weren't for ADH, a day on the beach would tantamount to a life threatening experience where you would dehydrate yourself to death within a matter of hours. It is the hormone that has helped life evolve from the oceans to land, eons ago. If it weren't for ADH, you and I would be ocean dwelling organisms, unable to withstand the harsher dehydrating influence of a hotter land surface under a blazing sun! 

So why am I talking about ADH? Well, studies have shown that ADH is one of the factors involved in the growth of the cysts (the reason for kidney failure) in PKD.

 In other words, if you could somehow inhibit the action of ADH on the cysts and consequently slow down cyst growth, you could possibly stem the inexorable progression of PKD. 

CURRENT TREATMENTS AVAILABLE FOR PKD

Understanding the role of ADH helps in understanding the treatment options available: from increased water intake to cutting edge drugs.

• Increased water intake: As simple as this sounds, one effective way to keep ADH levels down is drinking water. As we discussed above, ADH levels go up when you start to get dehydrated. This makes you feel thirsty, you drink some water, and ADH levels typically get lowered. In this case, the idea is to keep ADH consistently low by preempting ADH rise. It is postulated that this could slow the progression of PKD. How effective and meaningful is that in real terms is still debatable though.  
• In the absence of other specific treatments on the market, we are limited to managing the complications of PKD. These include high blood pressure, kidney infections, kidney stones, abnormal electrolytes etc. High blood pressure is treated using specific medications called ACE inhibitors or ARBs. Increased water intake might also help in reducing the risk of two other major PKD related complications-  kidney infections and stones. 
• My personal opinion based on the data available thus far is that even though increased water intake might not help in a major way, it is unlikely to hurt either.

FUTURE TREATMENTS THAT COULD ARREST POLYCYSTIC KIDNEY DISEASE PROGRESSION

Our understanding of the role of ADH in PKD, has led to research being done to come up with definitive treatment. Could we inhibit the action of ADH on the kidney and prevent cysts from growing? Enter tolvaptan, a medication that was originally approved for treatment of low sodium levels. Recently, the well-publicized TEMPO trial has shown a potential clinical application for tolvaptan in stemming the progression of PKD by slowing the growth of the total kidney volume and GFR decline over a 3-year period. Tolvaptan however has not received FDA's blessings for PKD treatment though, partly because of concerns about its effects on the liver. 

Another agent that is being studied for a few years for its potential role in inhibiting cyst growth in PKD is a drug called octreotide (a long-acting synthetic version of a hormone called somatostatin). This is an agent that we in the nephrology universe have been using for some time for the treatment of hepatorenal syndrome (a type of combined liver and kidney failure).  A trial had first reported in 2005 that a 6-month treatment with somatostatin could slow cyst growth. Although we know that decline in kidney function in PKD follows cyst growth, the study stopped short of saying that slowing the cyst growth in this case would translate in to clinically meaningful kidney protection. Then, in 2013 we saw the results of the ALADIN trial (this is officially my vote for the "coolest sounding medical study of the year" award!) published in the Lancet. This study had a longer follow-up period than the previous studies, and indicated a significantly lower kidney volume in patients treated with octreotide at 1-year follow-up, but not at 3-years.

Given the data we have so far, it appears that octreotide could have a potential role in the treatment of PKD. For some reason, it appears that octreotide slows growth in kidney volume over one year, but the effects become insignificant over the long term. Obviously, more comprehensive studies looking at long-term hard outcome data are needed. Another interesting thing would be to compare the data for octreotide vs. tolvaptan. 

Although both these agents have shown promise so far (in addition to other contenders like mTOR inhibitors), a major concern is cost. All other things being equal, octreotide could be a cheaper alternative than tolvaptan for what essentially could be a lifelong treatment.  At my time of writing this, a ten-day course of 15 mg tolvaptan pills was priced at $3440.00, while a 100 mcg octreotide injection was priced at $11.93!

A more comprehensive database of up-and-coming drugs that might be the magic cure for PKD is available here. I can’t wait for the day when we will be able to offer our patients something more definitive for treatment of PKD rather than the current “bandaid” regimen of ACE inhibitors, increased water intake, etc.