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NBME 21 Answers

nbme21/Block 3/Question#45 (63.7 difficulty score)
A 28-year-old man comes to the physician for ...
FructoseπŸ”
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 +12 
submitted by yo(86),
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I sujt wenk ahtt esmpr eedn efo,csrut ton esur wtha iadssee ropcses sith si uoth.gh eH aws yptret rlaomn os a5 adcstueare stod'en stpenre elik .taht I wa'stn eusr if eetrh swa yna odd sue of the oreht ssw.near eerh si a ln.ki Flee reef ot dneapx.

ca_7gs24qmsc2.wt:sp2/./npo/ehiaulbte.swpotwx

tcsouFre kmsea up 9%9 of eht ndigruec gasur ntsreep in .neems hsiT urgas is dropcued ni eht eainlms vecisles. eihdmiinDs elelsv of eurotfcs heva eben wsonh to llaaelrp drgonane denficeicy nda eth tessntteeoor ev.lle lilngowFo toesesoetrtn ypa,ehrt the vleel of cseftrou rnshioaAc.tehuelsg teh trecfuos stet si ont rtap fo a uetnior menes iasslnay, ti is seuflu ni sesac of moaeozprisa es(benac fo rpsme ni e)emsn. nI rozpoamiase rynaeodcs to teh bcnasee fo sleisvce ro fi eterh is na tnbicusr,oot no cseuroft si eep.ntrs nI lrtsaicute oraspam,ieoz ufrteosc si eers.ptn nheW ieaoomarzps dan owl smeen vouelm e,isxst eht crsutoef etts odushl sola be oen,d on a pucetastlojea erinu spalme ot ckche for dererratog eaju.coiltan Tihs occusr nhew teh lcejaatue egso noit teh lraddeb tnadsei fo uto eht rhau Teerht. perrceoud fro tmrenngiide het umnaot of rfotcsue ni esnem snovveli ithange senme in a rotsgn dcai in het eersepcn fo l.ocrnsorei touesFrc sivge a rde orcol fo(Soenfvli ecari)ton and may be arde ni a .otprteemho ehT anmrlo eaeravg si md/g51L3 crsefo.tu

sam.l  Thank you for the explanation. I'm still confused about this answer. I was in between Zinc and fructose. Zinc deficiency also presents with anosmia (pg 71 First Aid 2019). Fructose is used for the movement. His hormones are normal. +3  
d_holles  Apparently diabetes, occlusion, and inflammation can result in ↓ fructose in sperm. Mauss et al, Fert Stert 25, 1974 https://www.fertstert.org/article/S0015-0282(16)40391-2/pdf +4  
cienfuegos  Thanks all for the info, quick note on the Zinc reply above @Sam.I: anosmia = lost sense of smell. +  
sam1  Great find yo! I believe this question was alluding to cystic fibrosis and the congenital absence of the vas deferens. Here is a link to a NEJM article about it below: https://www.nejm.org/doi/full/10.1056/NEJM196807112790203 +  
burak  zinc deficiency cause hypogonadism. there is no hypogonadism, sperms are damaged? +  
fatboyslim  @Sam1 but cystic fibrosis will show abnormal physical findings (clubbing, pulmonary crackles etc). The question says physical exam shows no abnormalities. +  
pg32  Confused as to how we can rule out zinc... From medicalnewstoday.com: "Zinc also plays a role in healthy sperm production. According to a 2018 review article in the Journal of Reproduction and Infertility, zinc deficiency may contribute to poor semen quality and infertility." +  
bekindstep1  @pg32 I am not sure of how Zinc contributes to sperm production, but the question was asking about abnormalities in the semen and fructose is present in the semen. Maybe zinc plays a role in sperm development before it is mixed in with semen and so one with zinc deficiency wouldn't have low in zinc in their semen perhaps, but it their blood. This is just a hypothesis though.... +  
brise  ^^ Yeah that's how I ruled it out. You can find fructose in the semen, but you wouldn't be able to find zinc in the semen! It might help the sperm, but it's not going to be chilling with them +  

Increased WBCs indicate genital infection/inflammation, which can lead to poor semen quality due to the production of excessive reactive oxygen species by leukocytes.

Absent fructose concentration is an indication of a congenital absence of vas deferens/seminal vesicles, while decreased fructose concentration may indicate an ejaculatory duct obstruction.

pH > 8.0 indicates inflammation of the prostate, seminal tract, epididymis, etc.; pH < 7.2 indicates seminal vesicle dysfunction or obstruction of the ejaculatory ducts.

+/- apurva(76),


 +8 
submitted by nwinkelmann(294),
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So I lokdeo onit stih terrhfu oot ecabeus I etrpty cmhu konw ginothn tbuao teh mkae up fo eme.ns mrFo eht ersheacr I fnduo, sa as dtseta oblwe yb ,yo fcosture is eht omst anmpitotr tiesocnntut of mnsee in remts ro mrspe cinnou.tf elwoB si morintifoan I noduf to ardsesd teh roteh swrnea siohecc.

incZ ycfceiiden in( )ume,sr erp ,FA hsa eben ptaedcmiil ni lydedae noduw nhgla,ie rupsedspse nimym,iut alme ondipmyoagh,s recdedsae udlta iarh l(i,araylx flaa,ci u,pbc)i si,duyagse asia,mon itrsetcammrdiao ercaonptheiat (cfeted in teantisinl nicz obsrpit,)aon dna yam sprideoeps to olaoccilh cios.srhri AF itd'dn pseycif eht velsel ni teh es,emn tbu rpe teh lwboe reta,lic mnlesai cniz cnttnoe asw udfno ot evah ron itleoaonrcr to mmee/enpsrs iatevtecve/llytic./ I odn't nkwo fi wree' edsosppu ot oknw atht, but won I do, .llo npm/.su5hw3.dbvw.7cnpobg3/7eh5/.0ilw/ti:mnt.

As yuhxobrng meoenint,d mlneelsui is yoln emedninto onec ni FA as a erttemant for ,tniae so I lkdooe onit it ft.uhrer lSemnieu si a onntcet of esmn,e tub elelsv rayv os uhmc ahtt ti rvsese on tpcoiognrs lanilcc nerclveae to reiytinflti, erp tish r:lcieat nw.mb/3.s0ttimh5/lnwig/o2.cn31e:dw2b/ph.puv.

To uler out lla of the sranwse (ebescau I 'idtdn lreyal ownk ayntnhig auobt eth quatyil of e,n)ems I nodfu shti "yB -tissttatsi,c hrete wsa on tsnnaicifgi frdeeifcen in eht mnees Na tnctncanoeroi noamg the iftfderen rospug 7( spuorg ltoat dbase on emprs )ontuc, gctnndaiii hte fnagnisintcii lroe of Na in erspm .io."tlmyit duhb2nc5.lb2/wn/.ntovh/i1mwpepg7/.wm:t.is1.

niFayll, I don't khtni het pa-5hla trseucaed zmenye si ullacyta ni nee,sm utb I dclou be ogwrn. hEiert w,ay ti nudwt'ol eb nmlaylrbao tdvleeae or lwo if het rseteontotse levles rea mr.aonl

bartolomoose  as per goljan, selenium is involved in glutathione peroxidase +  
chandlerbas  selenium has a role in glutathione peroxidase. excess selenium = garlic breath, hair loss, and nail changes, might see peripheral neuropathy. deficiency (pt on TPN) = dilated cardiomyopathy +  
chandlerbas  also zinc aids in sperm motility https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4773819/ thats why i chose zinc but whateverrr im over it +  



 +3 
submitted by hungrybox(1040),
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niodgcrAc ot het MLE,US isl'enmues olyn esu si ni lsmeienu sifudle sa a nmeattert rfo a unfsgu delcla izeaaMassl pps (nieaT rcsoril.)veo




 +1 
submitted by meirchod(1),

I reasoned through this one since I learned that seminal vesicles heavily use Sorbitol Dehydrogenase (and ovaries & liver I believe too), which means they probably have a particularly important need for Fructose. So abnormal fructose in semen is probably not a good sign.

P.S. I wonder if the ancients did the taste-test on this one... (seemed to work well for diabetes)




 +0 
submitted by nwinkelmann(294),
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So I oolkde otin tsih rrfhtue too eaucesb I pytert mchu okwn thnniog boatu eth aemk pu fo nem.se Fomr eht ercehsra I n,fuod sa as etdsta lwobe by y,o uresftco is hte somt tnmtporai nnsctittueo of emsne ni mster or psmre c.ntfouin lweoB si ninoormiatf I nufod to rdsdase the threo awersn oce.hsci

nZic cycidenfie i(n ,rs)ume per A,F ahs eebn eimadltpic in eyeldad wudon ,nlgiahe desssprupe mmu,iityn meal omoahdsn,yipg dcaeesdre luatd hria (al,ixarly lfi,aac iu)bpc, ueagsysid, oians,am iirctmmseodaart iecahtroptnea (etdecf in niltinstea cizn bto)naio,psr nad yam ordseipsep ot coliaclho hr.rociiss FA i'ntdd ypeicfs eth svleel in teh s,emne ubt erp eht blewo lti,cera aelnmsi icnz ecottnn aws uodnf ot eahv nro aenorrtiolc to mmeen/ssrpe tcceveillvetiy./at/ I tdon' okwn fi 'weer opessdpu ot know ta,th ubt now I ,do ll.o /53w./heh/lt5.nmbs/.dwb:og3n0mw7cpp7tvnui.i.

As ugborxhyn tn,needomi eemlliuns is olyn imdntneoe nceo ni FA sa a etnteatmr orf a,tien so I lkdeoo otin ti hefrr.ut iulneSme is a ntnceto of ne,sme but velesl vyar os cuhm ahtt it evsrse on ocginopsrt illcnac clearneve ot finreiti,ytl pre htis ct:ierla /wpmh251wl:0.gvtnmhodc/s/i2n.pn3e3wi/u..tbb.

To lreu uot lal fo hte wsaersn ueseb(ca I ntdid' ryaell nwok gintyanh abotu the altquiy fo m)eens, I dufon thsi "By tcts-tasi,sit ether swa on sgatniiicfn inedefferc ni teh nemse aN notreiatocnnc mgaon eht dfrenietf ugsrpo 7( ugopsr altot adbes no smrpe co,tnu) ndtcainigi the agtcifisinnin orle fo Na ni mrspe it".loiym.t b2nbwclpw7ietn5gn./:.tsm/v1.1w//mhdiouh2.p.

n,ilFyal I d'tno nktih eth phla5a- urecdatse yezenm si cuatlyla ni eme,ns tub I duocl be gow.nr ihrEte w,ya ti olwn'tud eb loymnbarla eledavet ro wol fi teh tesortseonet lsevle aer nl.aomr




 +0 
submitted by apurva(76),

Increased WBCs indicate genital infection/inflammation, which can lead to poor semen quality due to the production of excessive reactive oxygen species by leukocytes.

Absent fructose concentration is an indication of a congenital absence of vas deferens/seminal vesicles, while decreased fructose concentration may indicate an ejaculatory duct obstruction.

pH > 8.0 indicates inflammation of the prostate, seminal tract, epididymis, etc.; pH < 7.2 indicates seminal vesicle dysfunction or obstruction of the ejaculatory ducts.




 -1 
submitted by flexatronn(2),

you all are looking way too deep into this.

This was a simple fact recall question. When you see semen + infertility in a question and fructose in the answers; its semen = fructose