Kid­ney stones are very com­mon in Trinidad and To­ba­go and ad­vice is not in short sup­ply. In­deed there are many myths that go along with this ad­vice. Folks of­ten ask about di­et and kid­ney stones as well as treat­ment op­tions. I have tried to sum­ma­rize the im­por­tant points in this ar­ti­cle. While an in­di­vid­ual may have spe­cif­ic re­quire­ments based on an as­sess­ment by his/her urol­o­gist, this ar­ti­cle deals with gen­er­al ad­vice for the av­er­age stone for­mer.

Di­et and kid­ney stones

Per­haps the best di­etary mod­i­fi­ca­tion you can make is to in­crease liq­uids in your di­et as lots of liq­uids pre­vent the urine from be­com­ing too con­cen­trat­ed. A good rule is to drink enough to make 2-3L of urine a day and for this we rec­om­mend wa­ter as your pri­ma­ry flu­id source. It is al­ways help­ful to car­ry around a wa­ter bot­tle for ease of ac­cess! You may con­sid­er adding some lemons to the wa­ter for fla­vor and this has the added ben­e­fit of al­ka­lin­iz­ing the urine which in it­self may help to pre­vent stones.

Oth­er di­etary rules to fol­low in­clude:

Re­stric­tion of an­i­mal pro­tein as these in­crease your risk of stones – this in­cludes fish. An­i­mal pro­teins should be used in mod­er­a­tion and some should take the form of dairy to en­sure that you are get­ting enough cal­ci­um. Gen­er­al­ly, you should lim­it foods with a high po­ten­tial re­nal acid load (PRAL). Foods with a high PRAL in­clude eggs, meat and ched­dar cheese. A list of high PRAL foods can eas­i­ly be found on the in­ter­net. There is no ev­i­dence that drink­ing “hard wa­ter” leads to an in­crease in kid­ney stones and hence bot­tled wa­ter is not nec­es­sary.

In the kid­neys cal­ci­um is ex­cret­ed along with sodi­um; as more sodi­um is eat­en and ex­cret­ed, there is a cor­re­spond­ing in­crease in cal­ci­um pushed in­to the urine and this could lead to kid­ney stones. You should there­fore lim­it your salt in­take as best as you can. Try not to add ex­tra salt and per­haps look to spices to en­hance fla­vor.

Many per­sons have com­plete­ly elim­i­nat­ed dairy from their di­ets and this is ill ad­vised. It has been found that re­mov­ing cal­ci­um com­plete­ly will in fact lead to an in­crease in stone for­ma­tion. We there­fore rec­om­mend eat­ing nor­mal amounts of cal­ci­um (1200mg/day) from both non-dairy and dairy sources. Cal­ci­um sup­ple­ments are a dif­fer­ent mat­ter and may in­crease your risk of stones and if you are a stone for­mer, should be avoid­ed if pos­si­ble. You should dis­cuss your spe­cif­ic needs/risk with your urol­o­gist.

You should use plen­ty of fresh fruits and veg­eta­bles which are high in cit­rate and have a low PRAL. Cit­rate is a po­tent in­hibitor of stone for­ma­tion. It should al­so be not­ed that cu­cum­ber and toma­to seeds do not lead to an in­creased risk of stones.

Cal­ci­um ox­alate is the most com­mon stone con­stituent and you should make an ef­fort to lim­it (not nec­es­sar­i­ly elim­i­nate) foods with a high ox­alate con­tent which in­clude choco­late, tea, soy, straw­ber­ries, and spinach. This is es­pe­cial­ly im­por­tant if you are known to form cal­ci­um ox­alate stones.

Treat­ment op­tions for kid­ney stones

For­tu­nate­ly, we have many treat­ment op­tions for stones in Trinidad and To­ba­go and choice of treat­ment will de­pend on sev­er­al fac­tors in­clud­ing stone size, hard­ness and lo­ca­tion as well as prob­lems the stone may be caus­ing such as in­fec­tion or block­age. A CT scan with or with­out an X-ray will help pro­vide valu­able in­for­ma­tion as will blood and urine test. Some stones may be small and may not re­quire any treat­ment at all.

The ureter is the tube which leads from your kid­ney to your blad­der and a stone lodged in this tube is ex­treme­ly painful! It can al­so be­come in­fect­ed and may even cause kid­ney dam­age. If the pain set­tles, your urol­o­gist may give the stone a chance to pass. This is an op­tion if the stone is small, usu­al­ly less than 1cm, and there are no signs of in­fec­tion or kid­ney dam­age. You may be pre­scribed painkillers as well as a tablet which re­lax­es the ureter and helps the stone to pass. If your stone is caus­ing an in­fec­tion your urol­o­gist will rec­om­mend place­ment of a stent which is a thin plas­tic tube that is placed through your urine tube and which runs from the kid­ney to the blad­der – this helps drain the kid­ney and the in­fec­tion. This pro­ce­dure does not re­quire a cut. De­fin­i­tive treat­ment will take place once you have re­cov­ered from your in­fec­tion as the stent alone is not a treat­ment for stones and should not re­main in place any longer than is nec­es­sary for you to have de­fin­i­tive treat­ment.

There are sev­er­al sur­gi­cal op­tions for kid­ney and ureteric stones:

1.Ureteroscopy – This in­volves pass­ing a very long, thin cam­era up the ureter and may al­so be used for stones in the kid­ney. This al­lows us to break the stone with a laser. Fol­low­ing this, the urol­o­gist may leave a stent in place for a few days. Ureteroscopy is quite a safe pro­ce­dure and may even be done as a day case.

2.Ex­tra­cor­po­re­al shock­wave lithotrip­sy (ESWL) – This ma­chine gen­er­ates shock­waves to break up kid­ney stones with­out mak­ing a cut. Once the stone shat­ters, the small frag­ments are passed out in the urine. This is a same day pro­ce­dure but you may re­quire some se­da­tion. Not every­one is suit­able for ESWL as hard stones make shat­ter­ing the stone dif­fi­cult and there are lim­its on the size of stones which can be shat­tered. Some pa­tients may need mul­ti­ple ses­sions for full clear­ance.

3. PC­NL - Pre­vi­ous­ly, we made fair­ly large cuts to re­move kid­ney stones and some sur­geons still of­fer this. A much more mod­ern and less in­va­sive op­tion is called per­cu­ta­neous nephrolitho­to­my or PC­NL. This is a good op­tion for larg­er stones in the kid­ney and for­tu­nate­ly is of­fered lo­cal­ly. A nee­dle is used to punc­ture the kid­ney through the side or the back and a wire is passed in­to the kid­ney. A tiny tract, usu­al­ly less than ? of an inch wide is de­vel­oped and a cam­era is placed in­to the kid­ney – the stone can then be bro­ken up with a stone break­er or laser. In this way there is on­ly a tiny cut on the skin and re­cov­ery is much faster.

You should dis­cuss your par­tic­u­lar case in great de­tail with your urol­o­gist be­fore de­cid­ing which op­tion is right for you

Satyen­dra Per­saud MBBS DM (Urol) FCCS FRCS

Con­sul­tant Urol­o­gist, San Fer­nan­do Gen­er­al Hos­pi­tal

Lec­tur­er in Urol­o­gy, Uni­ver­si­ty of the West In­dies