Catch-Up and Catch-Down Growth: A Review - GGH Journal

Catch-Up and Catch-Down Growth: A Review
James Tanner, M.D., D.Sc. den Growth Study and found that returned to a family environment
Associate Editor the deviations from the curve were characterized by semi-starva-..
Growth, Genetics, and Hormones greater in those children who had tion-the catch-up growth may.
many episodes of minor illness be only partial.4 In children
Growth in children is never consis- than in those who had only a few. with growth hormone deficiency
tent, Small variations occur sea- Such illnesses were not associ- (GHD) who are treated with growth
sonally. Frequently, significant al- ated with lower adult heights or hormone (GH), as illustrated in
terations occur with illness, even with reduced growth ve- Figure 1, striking initial catch-up
nutritional failure, the administra- locities considered over a year or growth occurs with treatment (14
tion of exogenous hormones, or more. Nevertheless the children cm/year in the first six months of
the increased production of endo- were nudged off course tem- treatment). However, full restoragenous
hormones. Following sig- porarily. tion to genetic potential.. as reprenificant
alterations in growth, com- When the interruption of growth sented by the parental target
pensatory catch-up or catch-down has been great, the restoring force height range shown in the upper
growth frequently occurs. This top- is also great, and when the failure right part of Figure 1, may not ocic
has been poorly understood. is repaired, the child springs for- cur in the long run.5 Perhaps the
The goal of this article is to provide ward to catch up to his previous difference between the extent of
an update on current concepts. growth curve. As he approaches catch-up growth in children with
his genetically predisposed chan- thyroxin deficiency and those with
Catch-Up Growth nel, the restoring force diminishes, GHD is rooted in the much greater
Under normal circumstances. a and the child's growth slows down delay in bone age that occurs in
child's increase in height follows a and proceeds as smoothly as be- hypothyroidism, or perhaps it is
very regular path, if considered fore. At least this is what happens simply that the child with GHD has
over periods of a couple of months in the most favorable circum- fallen much further below the noror
more. So regular is it, indeed, stances, eg, juvenile hypothyroid- mal percentiles for age than usuthat
the rate of such growth is one ism, where catch-up is almost ally occurs in hypothyroidism.
of the best indices of a child's gen- always complete, provided treat- In examining the final height of
eral health. Minor illnesses cause ment starts before the child is 30 boys with idiopathic isolated
minor irregularities: Rogers 1 fitted about 14 years of age.3 In less GHD who were treated continu-
Preece-Baines curves2 to the favorable circumstances-eg, ously with human growth hormone
heights of individual children fol- children who are admitted to the (hGH) until growth ceased of its ,
lowed longitudinally in the Harpen- hospital with kwashiorkor and then own accord, Burns et al6 found

that only the standard deviation "Compensatory deceleration" has the correlation coefficient had ris-
(SO) score for height at the begin- been suggested. The term "catch- en to 0.5; by one year, it had risen
t ning of treatment (with allowances down," however, originally sug- to 0.7; by two years the stable premade
for parental heights) was gested as a linguistic joke, seems pubertal value of 0.8 was reached.
important. The lower the SO score to have caught on. Not all children Thus, during infancy a reasinitially,
whatever the child's age, treated with GH exhibit this sortment of relative sizes among
the lower the final height, by some marked deceleration in com- children comes about: Those who
2.5 cm for each SO score below parison with pretreatment growth are larger at birth grow less; those
the mean for the group. Of the 6 SO rates. The reason for the differ- who are small grow more. Figure 3,
lost by untreated GHO patients be- ences between children remain from an old but comprehensive
fore GHO was recognized, we obscure. study,8 illustrates this. It should be
were able to restore 4 SO on aver- noted that the velocity curves for
age, but we were not able to re- Catch-Up and Catch-Down as weight of only the extreme birth
store the other 2 SO. This was true Normal Occurrences weight cohorts of 5 to 61bs and 9 to
even in patients who received In infancy, catch-up and catch- 10 Ibs are shown. In a classic patreatment
as early as four years of down growth occur as normal per, Smith et al9 described the
age.7 In those first few years of phenomena. Soon after the longi- same thing in American middlerapid
growth, a deficit that is only tudinal data for growth from birth to class, well-nourished babies.
partly recoverable seems to ac- maturity became available, it was In fact, the curves shown in Figcumulate.
We do not know why this shown that the correlat[ons be- ure 3 conceal heterogeneity. Not
is so. tween measurements taken in an all 9-pounders grow especially
individual child at various ages- slowly, only those whose genes
Catch-Down Growth birth, one month, three months, six specify an average adult size but
Catch-down growth is the oppo- months, and so on-and his or her whose maternal uteruS was highly
site of catch-up growth. If growth is measurements .as an adult had a stimulatory. Some of the 9-pound.:
artificially stimulated and then the characteristic temporal pattern. ers come by it honestly: large at
stimulating force is withdrawn, the The correlation between length at birth and large later. But the others
growth velocity drops for a while, birth and adult height was low (ap- slow down until they hit their
as shown in Figure 2. We need a proximately 0.3). By six months, proper curves. Likewise, the small
term for this phenomenon, and
~ none has been forthcoming.,
Figure 2. Catcn-down growth in a patient receiving growth
hormone on two occasions separated by a year without
treatment. The growth velocity off treatment is significantly
Figure 1. Partial catch-up growth in a boy with idiopathic lower than the pretreatment velocity. The growth
isolated growth hormone deficiency treated with velocity on treatment also wanes with extended treatment.
growth hormone. cm
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continued on page 10

Catch-Up and Figure 3. Weight velocity curves of cohorts of babies weighing 5 to 6 Ibs
Cat~h-Down Growth and 9 to 10lbs at birth. As a group. the smaller infants grow more rapidly
continued from page 9 than the larger infants. ()
babies with genes for average final ", Boys
height catch up to their proper ~ :~ (-'\,
curves, a process usually completed
by about 12 months. This
.~
Co
::
c,
was already well know~ to anim~1
~
3:
"
~: Birth weight
breeders: If a large Shire horse IS ~ ". (in pounds)
pony, crossed the with size of a the small newborn Shetland foal -: g '0 -g ~: "0 '0 ." '0 '0 00 90 ; '00 "0 '00 "0 "0
closely follows the size of the ~ g Age in weeks
mother.1O But the tiny foal of the ~ ~ :: Girls
Shetland mother has half of its
height-determining genes from its
.~:=.::
~ c.
,-'--
". '--,
great Shire father, just as the large .5 ::
Shire-mother foal has genes from
its small Shetland father. After a
nearly few months, the same the size. two foals are
~
~
.5 (,)
~:
".
o. '" 00 ~ '0.0 so 60 '0
Birth weight
(in p~unds)
00 90 , ~" "0 ...0 "0 "0 "0
The Mechanism of Growth
Age in weeks
Regulation
Catch-up and catch-down growth theoretically as maturity increases. Mosier thinks otherwise: The conare
simply exaggerated forms of If this is true, there must be another trol resides in a sizostat, which the
normal growth regulation. We do signal that tells the animal what irradiation has damaged. This is
not know how the extraordinary size it actually is, perhaps by syn- the explanation I gave for the seemprecision
of growth is maintained thesizing another series of mol- ingly unalterable short stature of
or how it is, for example, that ecules, this time in strict proportion children with early intrauterine lemonozygotic
twins who differ by to the amount of growth. Theoreti- sions (eg, Silver-Russell syn- .
3 cm in length at birth grow so that cally, these molecules would enter drome). Mosier has very recently.
there is only a 1-cm difference in the central nervous system to in- localized the effect of head irradiadult
height. We do not even know teract with the size-stuff and bind ation to the midline structures,
how the normal rate of growth is to it so that only a certain amount probably the suprachiasmatic
established or why the velocity of is left. This remaining amount is nucleus.
growth in general diminishes as the mismatch signal that controls This model may, of course, be
a child gets older. When we fit the output of growth-stimulating erroneous since the evidence is far
curves to the growth of individuals, hormone. from conclusive. Perhaps all reguwe
use equations, nearly all of
which assume that growth velocity
Recently, Mosier and his colleagues
12-14 designed experilation
takes place in the generative
and proliferative layers of carat
any time is a function of the ments to test this model. If rats tilage, with each cell having its inremaining
growth or, what is the have their heads irradiated shortly trinsic rhythm of division and gathsame
thing, the percentage of after birth, their subsequent ering a greater need to divide the
height completed. But how does growth will be stunted. If tested longer it lacks the necessary local
the child "know" what percentage later, after a 48-hour fast, their ca- hormone to do so. However this
he has attained? pacity for catch-up will not be im- may be, the physiology of normal
Many years ago, I suggested a paired; they catch up to their growth control is clearly the key to
"central" model to explain this,11 control-irradiated curve but not to understanding catch-up and
but "peripheral" models are also a normal-control curve. The catch- catch-down growth, as well as the
possible. In the central model it is up of normal rats starved for 48 effect of the various therapeutic
supposed that some sort of "sizo- hours is associated with an in- interventions now being used or
stat" exists in the central nervous creased amplitude but not fre- considered for the treatment of all
system; the sizostat tells the ani- quency of GH pulses, especially sorts of short stature.
mal what size it "ought" to be at during the light part of the light- References
The each .si.zostat moment could during do th!s its growth. by syn- dark rats secrete cycle. Although a lit~le less the GH irradiated t~an do Uni~er~~~r~Xf~rd,
1 RAM 'En~iand~~1~84.
Ph'l Th .0 x f ord
theslzlng and/or releasing every normal rats during both their con- 2. Preece MA Baines MJ. Ann Hum
so often, for example, a specific trol and catch-up growth, this does 8io/1978:5:1-24:
molecule not yet identified. The not necessarily mean the differ- 3. Van Harnack GA et al. Eur J Pediatr I
rate of synthesis would decrease ence in GH secretion.is causative. 1972;112:1-17.

4. Prader A et al. J Pediatr 1963; 8. Standards of normal weight in in- 12. Mosier HO Jr. et al. Growth
62:646-659. fancy. Ministry of Health Report, Public 1983;47:13-25.
5. Tanner JM. Br Med Bull 1981; Health No. 99. London, HMSO, 1959. 13. Mosier HO Jr. Pediatr Res,
37:233-238. 9. Smith OW et al. J Pediatr 1985;19:543-548.
6. Burns EC et al. Eur J Pediatr 1976:89:225-230. 14. Mosier HO Jr. et al. Pediatr Res
1981 ;137:155-164. 10. Walton A et al. ProcSocLond {Bioi] 1986:20:261-264.
7. Tanner JM. In: Human Growth, 2nd 1938;125:311-335.
edition, Vol 1. New York, Plenum, 1986, 11. Tanner JM. Child Dev 1963:
167-179. 34:817-847.