subjects with abnormal respiratory function, abnormal children aged 1 year or less, and the other including

Transcription

1 rch. Dis. Childh., 1965, 4, 33. THE RENL EXCRETION O HYDROGEN IONS IN INNTS ND CHILDREN BY LEXNDER PEONIDES, BRNETT LEVIN, nd WINIRED. YOUNG rom the Queen Elizbeth Hospitl for Children, London (RECEIVED OR PUBLICTION UGUST 24, 1964) The bility of the kidneys to excrete n cid urine is often ssessed by correlting plsm crbon dioxide nd urine ph. low plsm CO2 should be ccompnied by low urine ph, provided tht respirtory function is norml. Buchnn nd Komrower (1958) consider tht the renl excretion of hydrogen ions is norml in children if urine ph flls below 5, fter single dose of - g./kg. of mmonium chloride hs been given to produce metbolic cidosis. Under similr conditions, urine ph flls to below 5 2 in norml dults (Wrong nd Dvies, 1959). However, Elkinton, Huth, Webster, nd ccnce (196) found tht urine ph ws not suifficient to differentite ltent cses of renl tubulr cidosis in dults fter prolonged dministrtion of NH4Cl. These uthors suggested quntittive ssessment of the renl response to n mmonium chloride lod by the 'hydrogen ion clernce index' clculted s the product of the totl H+ excreted in the urine (meq/min./l -73 sq. m.) nd the plsm CO2 content (meq/1.) in subjects fter continuous NH4Cl dministrtion for 3-5 dys. bnormlly low vlues of the index were considered to indicte renl cidosis. This index hs not only proved sensitive one in cses with ltent renl tubulr cidosis, but lso useful in reveling the ltent renl defect in otherwise norml reltives of ptients with renl tubulr cidosis, thus contributing to our knowledge of the genetics of the disese (Huth, Webster, nd Elkinton, 196). In the present study the renl H+ excretion on norml diet, s well s fter the ddition of NH4Cl for severl dys, hs been investigted in order to determine vlues for the hydrogen ion clernce index in norml infnts nd children. Results from similr investigtions in children with renl tubulr cidosis nd their reltives will be reported lter. Subjects nd ethods Studies were crried out on 26 norml infnts nd children, mostly in-ptients who hd recovered from diseses not ssocited with renl or metbolic disturbnces. No subjects with bnorml respirtory function, bnorml plsm electrolyte or blood ure levels, or bnorml urines were included. Where necessry ure nd endogenous cretinine clernces were estimted, nd found to be norml for their ge. Since little is known bout younger infnts fter the neontl period, it ws thought desirble to divide the results now obtined into two groups, one including those children ged 1 yer or less, nd the other including children over 1 yer old. The younger ge-group consists of 12 infnts, 6 girls nd 6 boys, whose ges rnge from 2 to I 1 I months, 3 of whom were only tested while on norml diets, 8 while on norml diets nd lso fter NH4Cl hd been dded, nd one only during NH4Cl dministrtion. In ech cse, the infnts were fed on reconstituted dried cows' milk, with suitble semi-solid foods, except for one ged 2 months who ws on the milk mixture only. The older group consists of 14 children, 5 girls nd 9 boys, ged from 1 yer I month to 16 yers: 6 were tested both on norml diets nd fter NH4Cl hd been dded, nd 8 only while NH4Cl ws being given. Collection of Urine. Urine ws collected for period of four to nine hours (verge bout six hours) during the dy, ech collection being ccurtely timed. Older children were sked to empty their bldder directly into chemiclly clen bottles or pots. The urine ws collected from mle infnts by using Pul's tubing strpped round the penis, nd from femles by the use of metbolic bed. The specimens were refrigerted nd t the end of the test they were pooled nd nlysed immeditely for ph, titrtble cidity (T), titrtble cidity less bicrbonte (T -HCO3-) nd mmoni. In most cses the ph of the individul specimens of ech collection ws lso determined. luid intke ws incresed whenever possible in order to ugment the urine flow, nd thus minimize the error from incomplete emptying of the bldder. Incomplete collections due to lekge round the tube, or specimens contminted with feces, were discrded. blood smple for plsm CO2 content, nd in some cses for blood ph, ws tken bout the middle of the period during which urine ws collected nd two or three hours fter mel. 33 rch Dis Child: first published s /dc on 1 ebrury Downloded from on 3 y 218 by guest. Protected by copyright.

2 34 No. ISex I I en.. Rnge. ge (mth.) INNTS GED Norml Norml + NH4CI NH4C1 4 + NH4C NH4Cl NH4C NH4Cl I 11, PEONIDES, LEVIN, ND YOUNG Blood Diet Plsm Whole CO2 Blood (meq/l.) ph en..... Rnge. 19, I_ * TBLE 1 ONTHS: INDIVIDUL RESULTS, ENS, ND RNGE 36 l Rnge ph l * _ IPooled Specimens * T = Titrtble cidity Urine*,LEq/min./l 73 sq. m. NH4 + T OT- Totl HCO3 H _ * _ _ _ * * In ll the Tbles urinry excretions re expressed in.leq/min. /1 73 sq. m. nd not in meq, s in text, becuse of the smll mounts involved. Hydrogen Ion Loding. The renl response to n dded lod of hydrogen ions ws tested by giving NH4Cl, usully for three dys or in some cses for four or five dys. Since the results in those few who hd NH4Cl for the longer period did not differ significntly from the men vlues of the mjority who hd been given it for three dys, ll the results hve been nlysed together. The dose of NH4Cl ws from 6- to 9 g. ( meq)/dy/1 73 sq. m., the ctul dose being 1- to 7 5 g. dy ccording to surfce re. Ech subject hd the sme mount dily, divided in three to four doses given with or fter mels, to the younger children s mixture in syrup, nd to the older in uncoted cpsules. No side-effects were observed prt from slight vomiting in three subjects on the second dy of dministrtion, but this ws never severe enough to necessitte withdrwl of the NH4C1. few of the older children were given the slt t home, but ll cme into hospitl for the lst dy of the test. The urine ws collected during the lst dy of NH4C1 dministrtion s described bove, blood being tken two to three hours fter mel, when the subject hd lredy tken the first of the three or four dily doses of NH4C1. Cler- NH4+ nce in Index NH4X+ + T * The surfce re ws clculted from the height nd weight using the Du Bois nd Du Bois (1916) nomogrms. Lbortory ethods. PLS CO2 CONTENT. pproximtely 1 ml. cpillry blood, obtined by finger- or heel-prick, ws collected dropwise in heprinized 2 x 3 in. test-tubes without prffin oil. The plsm ws then seprted by centrifuging nd kept for nlysis within one to four hours. The CO2 content ws mesured mnometriclly (Vn Slyke nd Neill, 1924). BLOOD ph. This ws determined on cpillry blood collected in heprinized glss cpillry tubes, both ends of which were seled immeditely fter collection nd exmined within n hour fter smpling. The ph ws determined t 37 C. using microcpillry glss electrode (etrohm) nd ph meter with Vibron electrometer (Electronic Instruments Ltd.). URINE ph. This ws determined t room temperture by externl indictors using B.D.H. cpilltors. ONI. This ws estimted by ertion nd titrtion (Hwk, Oser, nd Summerson, 1954). rch Dis Child: first published s /dc on 1 ebrury Downloded from on 3 y 218 by guest. Protected by copyright.

3 RENL EXCRETION O H+ IN INNTS 35 The titrtble cidity of the urine ws determined by of infnts showed higher titrtble cidity thn the titrtion to ph 7 *4 with N/2 NOH. When the ph ws children, both before nd during NH4C1 dministrtion nd therefore smller proportion of H+ ws greter thn 6 2, titrtble cidity minus bicrbonte (T -HCO;-) ws mesured (lbright nd Reifenstein, 1948). excreted s NH4+. CLCULTION. The Hydrogen Ion Clernce Index = H+ excretion (meq/min./l *73 sq. m.) x plsm CO2 content (meq/l.). Where H+ excretion = T + NH4+- HC3- ech being expressed in meq/min./1 73 sq. m. Results The individul findings for the younger ge-group re shown in Tble I nd for the older in Tble 2. comprison of the results in the two groups shows tht both on norml diet nd fter NH4Cl hs been dded, the plsm CO2 ws bout 2 meq/1. lower in the infnts under I yer. Urine ph ws pproximtely the smre in the two groups, s ws the output of NH4+, though fter NH4C1, this ws little higher in the older group. However. the urine It is interesting to note tht under norml dietry conditions the totl H+ excreted by the older gegroup ws bout one-third less thn the mount excreted by the infnts. This my be explined by the fct tht the diet of children contins less protein per kg. body weight thn tht of young infnts who re being fed minly on cows' milk, nd the reltively lrge mount of phosphte in cows' milk lso contributes to the excess of T in the urine. fter the cid lod, the totl H+ in the urine of both groups ws the sme but the proportion of T remined higher in infnts, the children compensting by n increse in mmoni production. There is no mrked difference between the two gegroups in the men vlues of the H+ clernce index fter NH4Cl dministrtion, though by exclusion of one exceptionlly high index in the infnt group TBLE 2 CHILDREN GED 1 YER ND 1 ONTH TO 16 YERS: INDIVIDUL RESULTS, ENS, ND RNGE ge No. Sex (yr.) Diet 1 1 1/12 I 2 1 4/ /12 + NH4C I 4 2 6/12 + NH4Cl 5 3 4/12 + NH4C en.. Rnge. en.. Rnge / /12 5 9/12 + NH4C1 8 3/12 + NH4Cl NH4Cl.. Plsm C2 (meq/1.) Blood Whole Blood ph * Urine ph.leq/min./l 73 sq. m. Pooled T Rnge Speci- NH I + T HCO3 - mens _ _ _ _ _ Sl-5-2 5* _ _ T = Titrtble cidity _ _ _ Totl H I * % H+ NH4 + Clerin nce NH4+ Index + T J rch Dis Child: first published s /dc on 1 ebrury Downloded from on 3 y 218 by guest. Protected by copyright.

4 36 Z- C} E C Z E i2- I n I *O' 4 * %X 1\ PEONIDES, LEVIN, ND YOUNG k Totl hydrogen ions in urine (ueq/min./l-73sq. m.) IG. 1.-The reltion of plsm CO2 content to the rte of totl hydrogen ion excretion in urine (infnts nd children). The interrupted line shows the limit of norml vlues. 1-L E C~ IE Urine ph r~ t I1 8: E l I S O.* %% * * Ss *., "\ 's % *5 4 Urine ph IG. 2.-The reltion of plsm CO2 content to urine ph (infnts nd children). The interrupted line shows the limit of norml vlues. Symbols s in ig. 1. * Infnts Cnorml diet) Infnts C3rd dy NH4CI dministrtion) Children (norml diet) Children C3rd dy NH4CI dministrtion) IG. 3.-The reltion of mmonium ion excretion to the ph of urine (infnts nd children). The bold line is the men nd the interrupted lines represent the 95% confidence limits for dults (Wrong, 1961). Symbols s in ig rch Dis Child: first published s /dc on 1 ebrury Downloded from on 3 y 218 by guest. Protected by copyright.

5 RENL EXCRETION O H+ IN INNTS 37 lower men index would hve been obtined. This mesured by Elkinton et l. (196), since urine is due to lower plsm CO2 vlues rther thn lower pssed t night tends to be more cid thn tht totl H+ excreted in the urine. during the dy. urthermore, both the mels nd The index in subjects receiving free diet vried the divided doses of NH4Cl dministered during the widely. It cn be very low or even negtive if the collection period my hve resulted in rpid nd diet is lkline, when the subject is excreting more brief chnges in the blood chemistry nd the urine HC3- thn NH4+ nd T together. In these cses cidity, but blood for nlysis ws lwys tken t the renl bility to excrete H+ cn be ssessed by the sme time fter mels to offset this possibility. plotting the plsm CO2 ginst totl H+ excreted in The norml cpillry plsm CO2 content in this the urine. In ig. 1 the results for both infnts nd study rnged from 19-2 meq/l., which is lower children on norml diets nd fter NH4Cl dministrtion hve been plotted in this wy. The for rteril plsm in dults. The dropwise collec- thn the rnge given by Singer nd Hstings (1948) interrupted line joining the lower points of the grph tion of blood, nd the omission of prffin oil in the indictes the lower limit of the vlues for the infnts: collecting tube my hve contributed to these lower the lower norml limit for children is slightly higher vlues. In this lbortory, blood is no longer thn the one for infnts. Infnts or children whose collected under oil becuse of the prcticl difficulties, one of which is lwys ensuring dequte mixing vlues fll below this line my be considered bnorml s fr s renl bility to excrete H+ is of drops of cpillry blood under oil. Gmbino concerned. ig. 2 similrly shows the reltion (1961) hs drwn ttention to the fct tht minerl between plsm CO2 nd urine ph. ig. 3 shows oil my result in big losses of CO2 due to its high the NH4+ output in reltion to urinry ph nd solubility in oil. The routine method in this includes lso the norml limits nd the men for lbortory is to equilibrte the specimen with dults given by Wrong (1961). Under norml lveolr ir only if it is not nlysed within three to dietry conditions the vlues for ll our control four hours fter its collection, but this hrdly ever subjects except two-one infnt nd one child-fell needed to be done in the present investigtion. within the norml limits for dults, while fter or comprison, the findings from our infnt stressing with NH4C1, severl of them exceeded the group hve been tbulted together with those from upper limits of norml for dults. infnts ged 2-1 months recorded in the literture The percentge of H+ excreted s NH4+ is useful (Tble 3). Unfortuntely s the technique nd index of mmoni production. Our lowest figure methods of investigtion mong the different uthors for this percentge is 32 7 in infnts nd 37 in hve differed, the results my not be entirely comprble. Thus, Gordon, cnmr, nd Benjmin children. ccnce, theson, Greshm, nd Elkinton (196) consider tht figures below 3% (1948) nd ccnce et l. (196) nlysed 24-hour indicte impired mmoni production. Two of the urine specimens, while omon, Hrris, nd Jensen present subjects whose rtio of mmoni to urine (1959) used 12-hour night specimens of urine. The ph ws below the norml limits for dults (s shown ltter uthors nlysed venous blood nd this gve in ig. 3) lso hd comprtively low percentge of higher vlues of CO2 content in their series thn in H+ excreted s NH4+, but this incresed in one of ours. The H+ output of our infnts is higher thn them, who ws tested fter NH4Cl, from 37-2 to in the brest-fed infnts reported by omon et l nd in the rtificilly fed infnts by ccnce et l., but it is much lower thn tht of the infnts fed on Discussion cows' milk investigted by Gordon et l. (1948) nd Though the tests were rrnged so tht the results omon et l. (1959). Low H+ excretion is to be could be compred with those of Elkinton et l. expected in brest-fed infnts compred with those (196) for dults, there were difficulties in doing this, who re rtificilly fed, but it is difficult to explin nd the findings re not exctly comprble. the lrge differences observed mong infnts fed Difficulties in obtining ccurte 24-hour specimens rtificilly (Tble 3), unless their diets were quite were voided by using short periods of urine different, especilly with regrd to protein consumption. collections tht did not require dmission to hospitl overnight. further dvntge in this procedure is The output of H+ by our norml infnts (66 meq/ tht the urine could be nlysed without dely, thus 24 hr./l *73 sq. m.) under normrl dietry conditions minimizing the risks of chnges due to bcteril is pproximtely the sme s by two infnts, ged 8 ctivity. Rtes of dily H+ excretion clculted from months nd 1 yer, studied by Widdowson nd short period of the dy re probbly not representtive of the verge rtes for the whole 24 hours, 1 73 sq. m. surfce re, ssuming ech ws ccnce (1958) (if their output is clculted per of rch Dis Child: first published s /dc on 1 ebrury Downloded from on 3 y 218 by guest. Protected by copyright.

6 38 PEONIDES, LEVIN, ND YOUNG TBLE 3 EXCRETION O HYDROGEN IONS IN NORL INNTS ON NORL DIET ND TER ONIU CHLORIDE: PRESENT SERIES ND SOE PREVIOUSLY PUBLISHED IGURES Urine Plsm H + Group ge CO2 ieq/min./l 73sq.m. % of Cler- uthor (No.) (mth.) Diet Content NH4+ nce (meq/l.) in Totl Index NH4+ T H+ Excretion Gordon et l. (1948) Infnts 2-4 Cows' milk Venous *5 52 *7 37 * 2-19 (3) Cows' milk + NH4C I Venous 2* * 59 * 2*71 omon et l. (1959) Infnts 2-5j Cows' milk Venous 23 * * 45 *2 3 *24 (4) Cows' milk + NH4CI Venous 17*5 118* 82 * 59 * 3 *6 omon et l. (1959) Infnts 3[-4j Humn milk Venous <-56 (4) Humn milk + NH4C I Venous 15*5 48 *9 13* *97 ccnce et l. (196) Infnts* 1 diet t17 7 t Humn diet + NH4C1 t37*2 t21 *O 64 O Present Series Infnts ( 1) rtificilly fed Cpillry 19*9 2*4 25* *88 (9) rtificilly fed + NH4C I Cpillry 16*6 54*4 42*5 55*8 1*61 * The number of ptients included is not stted. The series includes some infnts studied by the uthors, nd others tken from published reports t Clculted from uthors' dt. TBLE 4 EECT O NH4CL DINISTRTION ON RENL EXCRETION O HYDROGEN IONS: NORL INNTS ND CHILDREN (PRESENT SERIES) ND PREVIOUSLY PUBLISHED VLUES IN DULTS en + en Totl H + H Clernce Index uthor Group (No.) ge Plsm Excretion CO2 in Urine (meq/l.) 1(1LEq/min./ en Rnge 73 sq. m.) Present series Infnts (9) 2-1 mth. Cpillry 16* *44 Present series Children (14) 13 mth.-16 yr. Cpillry Elkinton et l. (196) dults (17) Venous (serum) norml body weight nd height for ge) nd by dults reported by Elkinton et l. (196). ll re much higher thn those for infnts on the first, second, nd eighth dy of life (Widdowson nd ccnce, 1958). The response to NH4Cl induced cidosis by both infnts nd children in our series (Tble 4) is prcticlly the sme s tht in dults (Elkinton et l., 196), though the clernce indices of dults re slightly higher owing to higher serum CO2 levels. The present observtions indicte tht the kidneys of the children exmined were ble to cope s efficiently with the stress of H+ dded to norml feeding s those of dults. Htemi nd ccnce (1961), investigting the response of newborn infnts to single dose of NH4Cl, found tht H+ excretion ws much less thn in dults fter similr stress, the men clernce indices in newborns being only 21 % of their men dult vlues. Our results now show tht in the infnt the specific renl function of cidifying the urine under stress hs, presumbly by process of mturtion, chieved dult level by bout 3 months of ge. Though the number ofthe younger infnts exmined in this series is not lrge enough to suggest the erliest ge t which this mturtion occurs in ny individul, the results cn be used s bsis for the ssessment of cidosis of renl origin with incresing confidence over the ge of 3 months. Summry The renl bility to excrete hydrogen ions ws ssessed in 12 norml infnts ged months nd 14 children ged 1 yer 1 month to 16 yers on ordinry diets, nd in most cses on the third dy of continuous mmonium chloride dministrtion. Titrtble cidity nd mmonium ion excretion in the urine nd the crbon dioxide content in the plsm were determined within the sme period, nd from these vlues the hydrogen ion clernce index hs been clculted for ech child. The men nd rnge for the index in both ge-groups, s well s the totl hydrogen ions excreted/ I*73 sq. m. surfce re, were found to hve reched dult levels. It is considered tht the vlues for these norml children re suitble to use s stndrd tht cn be pplied in ssessing whether cidosis is, or is not, primrily of renl origin in children from the ge of bout 3 months. rch Dis Child: first published s /dc on 1 ebrury Downloded from on 3 y 218 by guest. Protected by copyright.

7 REERENCES lbright,., nd Reifenstein, E. C., Jr. (1948). The Prthyroid Glnds nd etbolic Bone Disese. Willims nd Wilkins, Bltimore. Buchnn, E. U., nd Komrower, G.. (1958). The prognosis of idiopthic renl cidosis in infncy with observtions on urine cidifiction nd mmoni production in children. rch. Dis. Childh., 33, 532. Du Bois, D., nd Du Bois, E.. (1916). Clinicl clorimetry. X. formul to estimte the pproximte surtce re if height nd weight be known. rch. intern. ed., 17, 863. Elkinton, J. R., Huth, E. J., Webster, G. D., Jr., nd ccnce, R.. (196). The renl excretion of hydrogen ion in renl tubulr cidosis. I. Quntittive ssessment of the response to mmonium chloride s n cid lod. mer. J. ed., 29, 554. omon, S. J., Hrris, D.., nd Jensen, R. L. (1959). cidifiction of the urine by infnts fed humn milk nd whole cows' milk. Peditrics, 23, 113. Gmbino, S. R. (1961). inerl oil nd crbon dioxide. mer. J. clin. Pth., 35, 268. GOrdon, H. H., cnmr, H., nd Benjmin, H. R. (1948). The response of young infnts to ingestion of mmonium chloride. Peditrics, 2, 29. Htemi, N., nd ccnce, R.. (1961). Renl spects of cid-bse RENL EXCRETION O H+ IN INNTS 39 control in the newly born. III. Response to cidifying drugs. ct pedit. (Uppsl), 5, 63. Hwk, P. B., Oser B. L., nd Summerson, W. H. (1954). Prcticl Physiologicl Chemistry, 13th ed., p Churchill, London. Huth, E. J., Webster, G. D., Jr., nd Elkinton, J. R. (196). The renl excretion of hydrogen ion in renl tubulr cidosis. III. n ttempt to detect ltent cses in fmily; comments on nosology, genetics nd etiology of the primry disese. mer. J. ed., 29, 586. ccnce, R.., theson, W. J., Greshm, G.., nd Elkinton, J. R. (196). The cerebro-oculr-renl dystrophies: new vrint. rch. Dis. Childh., 35, 24. Singer, R. B., nd Hstings,. B. (1948). n improved clinicl method for the estimtion of disturbnces of the cid-bse blnce of humn blood. edicine (Bltimore), 27, 223. Vn Slyke, D. D., nd Neill, J.. (1924). The determintion of gses in blood nd other solutions by vcuum extrction nd mnometric mesurement. J. biol. Chem., 61, 523. Widdowson, E.., nd ccnce, R.. (1958). The development of cid-bse control. In Cib oundtion. Colloqui on geing, Vol. 4, p. 29. Churchill, London. Wrong,. (1961). Personl communiction quoted by Berlyne, G.. in Distl tubulr function in chronic hydronephrosis. Qurt. J. ed., 3, , nd Dvies, H. E.. (1959). The excretion of cid in renl disese. Qurt. J. ed., 28, 259. rch Dis Child: first published s /dc on 1 ebrury Downloded from on 3 y 218 by guest. Protected by copyright.