Dolecek R., Tymonova J., Adamkova M., Kadlcik M., Pohlidal A., Zavodną R.

Medical School Hospital, Ostrava, Czech Republic

SUMMARY. Any major burn is followed by a pronounced endocrine and metabolic response, by an acute phase response. In 30 burn subjects whose bone status was studied after burn trauma with the densitometer HOLOGIC 2000. bone involvement was found 6 and 12 months postburn: the Bone Mineral Density (BMD) of their lumbar vertebrae L1-4 and of their left hip dropped significantly in most of them. Elevated levels of cortisol both in blood and in urine (free cortisol) were found, accompanied by very low testosterone, dihydrotestosterone (DHT) and free testosterone levels in blood of the burned males, but not of the females. Elevated 17(3-estradiol levels were found in many burned males; they were generally not low in the burned females. DHEA-S levels were generally low. Very low levels of the triiodothyronine (T3) and of the free thyroxine (FT4) were found. Increased, even very high, PTH values were occasionally present. hGH and IGF-1 were generally normal, with a few exceptions (low or increased levels). Total and ionized calcium levels were low after burn, 250H vitamin D (calcidiol) was usually low or low normal too. Prolonged and very high levels of CTX and of NTX (both are indicators of bone resorpcion, of collagen catabolism) were found, as well as of the ACP (acid phosphatases), but the latter were less manifest, if compared with the CTX and NTX. ALP (alkaline phosphatases) were elevated too, but their elevated levels were much less pronounced than the levels of CTX and NTX. Osteocalcin levels were initially low to low normal, to increase later to the normal levels. As for the cytokines that had been investigated, mostly the elevated levels of TNFa were found, as well as those of IL-2. IL-6 and IL-S. Finally, a few suggestions have been given regarding the additional possibilities how to treat the burned patients: the use of anabolics, of vitamin D, of calcium, eventually of calcitonin.

ZUSAMMENFASSUNG
Endokrine Veranderungen nach der Verbrennung: Die Knochenbeschadigung.

Jeder schweren Verbrennung folgt eine intensive innersekretorische and metabolische Reaktion. Bei 30 verbrannten Patienten wurde der Knochenzustand nach der Verbrennung mittels eines Denshometers bewertet. Die Knochenbeschadigung wurde sechs and zwolf Monate nach dem Unfall beurteilt. Die Dichte des Knochenminerals (BMD) wurde bet den mersten Lendenwirbeln L1-4 and den linken Schenkelbeinhalsen deutlich reduzart. Es wurde erhbhter Kortisol-Spiegel im Blut and Horn (Bog. freies Kortisol), Bowie uedriger Testosteron-Spiegel. Dihydrotestosteron-Spiegel (DHT) and freies Testosteron bet den verbrannten Mannern festgestellb. Bei mersten verbrannten Mannern wurde such erhohter 17[3-Estradiol-Spiegel gefunden. Der Spiegel des Dehydroepiandrosteronsulfats (DHEA-S). Trilodthyronln (T3) and freies Thyroxin (FT4) waren allgemein niedrig. Genauso honer oder sehr hoher Spiegel des Parathormons (PTH) warden manchmal gemessen. Sowohl der somatotropen Hormon-Spiegel (8TH, hGH), als ouch der IGF-I-Spegel waren ausser elnigen Ausnahmsfalle normwertig. Der Gesamtkalzium-Spiegel, ionisierte Kalzium-Spiegel and 2501 Vitamin D-Spiegel (Kalcidiol) waren nach der Verbrennung ridding.Bei der Mediatoren der Knochenresorption and des Kollagenkatabolismus, CTX and NTX, wurde erhbhter Spiegel wiederholt festgestellt. ACP- and ALP Spiegel waren genauso erhdht, obwohl nicht so deutlich we bet CTX and NTX. Osteekalcin-Spiegel war am Anfang niedrig oder normal, spMer behand sich im Bereich der Normwerte. Was die Cytokinen betrifft, erhohterTNFa-Spiegel, IL6-Spiegel. IL-8- Spiegel and IL-2-Spiegel warden beobachtet.ln dem Beitrag ward ansfuhrlich die Bedeutung der Reaktion der Akutphase nach der Verbrennung. Abschliessend werden die Mdglichkeiten einer Erganzung der Therapie von verbrannten Patienten mit Hilfe von den Anaboliken, Vitamin D; Kalzium and eventuell such Kalzitonin angefuhrt..

Key words: burn stress, acute phase response, bone disease, bone resorption, gonadal hormones, thyroidal hormones, PTH, calcium, CTX, cytokines, phosphatases, calcidiol, densitometry

The stress response to any major burn is followed by a marked metabolic and endocrine response (for reviews see e. g. Dolecek, R., 1960, 1969; Sevitt, 5.,1974; Davies, JWL., 1982; Dolecek, R., 1984; Dolecek, R., Brizio-Molteni, L., Molteni, A., Traber, D.,1990; Dolecek, R., 2002) as well as by an acute phase response (e. g. Dinarello, CA., 1984: Berczi, l., 1998) (Tab. 1), accompanied by muscle wasting (for its pathogenesis see e. g. Hasselgren, PO., Fischer, JE., 2001). At the same time the skeletal system is usually involved as well; the term bone disease has been used for this phenomenon (Klein, GL., 1993). The bone involvement may be seen from the altered levels of various markers of bone metabolism (e. g. ALP, ACP, CTX, osteocalcin), and from the densitometric changes found in bones 6 and 12 months following the burn injury (Dolecek, R., 2001). Osteoporosis after burn trauma has often been described, begining with the paper by Owens N. (1949), followed by many other authors (Colson, OP., 1956; Artz, CP, & Reiss, E., 1957; Evans, EB., 1959; Dolecek, R. & Stepanek, V., 1959: Kol,qr J., 1959 etc.). The cytokine levels are also altered after burn trauma and trauma in general (IL-1(3, IL-2, IL-6, IL-8, TNFa, etc.) (e. g. Srost, AC., 1993; Kantorovd, I, 1995.). Avery detailed study of the biologic basis of interleukin-1 (IL-1) in disease was published by Dinarello, CA. (1996); interieukin6-type cytokines in various clinical conditions were described in detail in a monograph edited by Mackiewicz, A. (1995).

MATERIALS AND METHODS

In the Burn Center at Ostrava 30 burn patients, 27 males and 3 females, most of them with major burns, were followed (Tab. 2). Their mean Burn Index (BI) (x ± SD) was 21.1 - 13.4 (8-59). The HOLOGIC 2000 densitometer was used to study their bone density, as soon as it was possible to examine the patients. There after their bone density was measured after 6 and 12 months. Lumbar vertebrae L1-4 and the left hip were studied (Tab. 2). The mean age of the males was 40.1 ± 16.3 (18-74) years. At the same time, levels of various hormones, as well as of various indicators of bone remodelling (formation/resorption) in blood were investigated not only in those patients but in other burn patients too: cortisol, testosterone, DHEA-S (dehydroepiandrosterone sulphate), dihydro testosterone (DHT), free tes tosterone, 17(3-estradiol, tri iodothyronine (T3), free thy roxine (FT4), hGH (growth hormone), IGF-I (Insulin like Growth Factor), PTH (parathyroid hormone), total and ionized calcium, inor ganic phosphate, alkaline (ALP) and acid (ACP) phos phatases, osteocalcin, 25-hydroxycholecalciferol (calcidiol, 250H vit. D), Cterminal of procollagen I peptide (CTX), in some cases the N-terminal (NTX) as well, together with the free cortisol in urine. In some burn patients the interleukins 1[3, 2, 6, 8 and TNFa were evaluated. The above indicators were measured in the Laboratories of the Department of Nuclear Medicine and in the Central Laboratories of the Medical School Hospital in Ostrava. The Burn Index (BI) = 1% of the body surface of a II' burn means 1/2 point, 1% of the III° burn 1 point.

RESULTS

  If compared with the first densitometry soon after the burn trauma, the bone mineral density (BMD) decreased - often dramatically - after 6 and 12 months in the majority of burn patients, especially in the lumbar vertebrae (Tab. 2). This decrease is expressed as the average change in the absolute value of the BMD in g/cmz, calculated per year. Table 3 depicts the mean values (x ± SD) of various indicators in 15 burned men, with a mean age of 39.1 ± 20.1 years, (17-74), with BI 24.8 ± 12.6 (8-46). The elevated values are printed in bold, the decreased values in italics. For comparison with different polytraumas Table 4 is included. Some of the burn patients were earlier followed up to 2 years, to see the return to "normality" of their various hormonal levels. In Table 5 a critically burned patient (NN) is presented, in whom even the results of Insulin Tolerance Tests were different when studied one year and two years after the burn trauma. The tests after two years were "more normal", i. e. the hGH and cortisol responses after insulin caused hypoglycemia were normal. The extremely low levels of testosterone, dihydrotestosterone (DHT) and free testosterone are presented in a critically burned male patient with polytrauma and postburn shock who died later (Tab. 6). At the same time his bone remodelling indicators (resorption/formation) were very high (CTX, ALP), while the thyroid hormones were extremely low, especially the T3. In the critically burned man MV (26 years old) the bone resorption indicators (CTX) were very high even one year after the burn trauma (Tab. 7). His T3, testosterone and dihydrotestosterone levels were very low for many weeks, while his DHEA-S values were unexpectedly rather high after burn trauma (helping him to survive?). His 17(3-estradiol levels were repeatedly elevated - probably a positive sign again. Another critically burned man (DD, 24 years old, BI 46) is presented in Table 8. Very low ionized calcium levels were found in him even after one year postburn. He had very high free cortisol levels in urine, extremely low testosterone levels for many weeks. Table 9 shows the results in a less severely burned man (PS, 30 years old, BI 15) who had very low levels of 250H vitamin D (calcidiol). They were low even one year after the burn. His DHT and calcium (total and ionized) were also low. Low normal and/or decreased calcidiol (250H vit. D) levels accompany usually polytraumas (Tab. 4) and burns (Tab. 6). For burn patients in whose blood various cytokines had been measured, elevated levels of IL-2, IL-6, IL-8 and especially of TNFa (tumor necrosis factor, cachectin) were found. The highest TNFa level found was 32 pg/ml in a critically burned female patient (normal levels are < 8 pg/ml).

  In elderly subjects, the prognosis after major burn is usually less favorable than in the younger ones. Table 10 presents such a case with a favorable outcome. The severely burned man W (74 years old, BI 32) was followed for one year. His testosterone and DHEA-S levels were very low during the whole time, his ionized calcium and triiodothyronine were repeatedly decreased as well, while the PTH levels were three times elevated. Probably the repeatedly higher 17(3-estradiol levels were a favorable sign. But his bone mineral density (BMD) six months and one year after the burn trauma, respectively, was substantially reduced, both in his lumbar vertebrae and in his left hip. Finally Table 11 includes two burn patients who did not survive their burn trauma. The male patient JK (63 years old, BI 15, with severe ischemic heart disease, with a pronounced status lacunaris) died 9 days after the burn. His 17[3-estradiol levels were very high, especially on day 8 postburn, one day before he died. The female patient JP (43 years old, BI 44, with lungs involved) suffered a severe burn. The NTX levels were high in both patients, the hGH value was once elevated in the female patient. But what was especially interesting in both patients were the enormous PTH values, the elevated ACP, and especially the low total and ionized calcium levels in the burned female. The cortisol levels in the burned male JK (>2000 nmol/1) were extremely high. Both T3 and FT4 were (with one exception only) extremely low in both burn subjects.

DISCUSSION

The main indicators of the burn stress in male subjects were testosterone, dihydrotestosterone (DHT) and free testosterone; they were low to very low, their low levels persisted occasionally for many weeks, even for months (Tab. 5). Almost the same may be said about DHEA-S, its elevated levels after burn are exceptional (Tab. 7). Those two findings mean a lack of anabolic hormones. Oddly enough, the 17(3-estradiol is quite often elevated in burned males; its levels usually reach the upper limits of its normal values in them. It is not decreased in the burned females. In earlier studies (Dolecek, R., Brizio-Molteni, L., Molteni, A., Traber, D., 1990) the testosterone levels in male subjects dramatically dropped after the ACTH administration, while they increased significantly in the females. In both the old males and females (but not in the young ones), 17(3estradiol levels increased significantly after ACTH.

At the same time the catabolic cortisol is either elevated or is near the upper limits of its normal values after burn trauma in both sexes. In Table 11 it was as high as >2000 nmol/1. The free cortisol in urine is more often high to very high: occasionally it reaches the high levels of a patient with Cushing's syndrome. Sensitive indicators of the burn stress in both males and females are the levels of the thyroid hormones, especially the triiodothyronine (T3) (Tab. 5, 6, 7). The prolonged very low levels of both T3 and FT4 may often signal a poor prognosis (Tab. 11).

Low levels of both total and ionized calcium accompany most cases of burn trauma (Tab. 3, 5, 8, 9, 10, 11). As a response to it, obviously to maintain the calcium homeostasis, elevated (Tab. 5, 8, 10) or upper normal levels of PTH may be found. Sometimes they are extremely high (Tab. 11). The same findings may accompany severe traumas, where PTH levels above 100 pg/ml were found too (see Tab. 4, footnote). The indicators of bone remodelling, both resorption (CTX, NTX, ACP) and formation (ALP, partially osteocalcin) are almost always altered after burn. The bone resorption indicators are elevated, often very much so, as a consequence of damages to the skin, to its collagen, but the bones are involved after burn as well, as a consequence of an unopposed catabolism. The locally increased TNFa levels may obviously play an important role here, too. The densitometric changes show this quite clearly (Tab. 2). The hGH levels were usually not greatly altered after bum; they usually remained low, but occasionally elevated levels were found (Tab. 5, 8, 11). As for the IGF-I, its levels were normal on average, but in some critically burned patients they were low immediately after burn (Tab. 8, 10, 11). Elevated levels were also found, probably as a favorable sign of anabolism (Tab. 3, 7, 9). A very interesting and somewhat unexpected finding was the low normal or even very low levels of 25011vitamin D (calcidiol). They could perhaps play a role in the low blood calcium levels. Those low levels could be caused by an impaired synthesis of D3 vitamin, caused by an elevated presence of glucocortivoids. The low vitamin D levels could impair the calcium resorption from the small intestine; they could even unfavorably influence the status of bones. Those unfavorable findings are potentiated in the elderly, whose intestines are less sensitive to the vitamin D3 presence.

The first results thus far obtained in this study regarding the cytokine presence in blood were very interesting: IL-2, IL-6, IL-8 and TNFa had elevated levels in burn subjects, and the TNFa. IL-2, IL-6 was especially high. TNFa are the endogenous pyrogens (see the high fevers so often accompanying major burns), and all of them are closely connected with the Acute Phase Response (Tab. 1). IL-6 exerts a direct influence on hypothalamus, on the anterior pituitary (it passes the blood-brain barrier), even on the adrenal cortex (for a review see Dolecek, R., Brizio-Molteni L., 1990, p. 41). TNFa stimulates the bone resorption (Bertolini, DR., 1986), decreasing the production of the utilizable energy in ATP by releasing the thermal energy (fever!), resulting in a severe drain of energy (Ruddle, NH., 1987) - all that could contribute to cell death.

Finally, a few therapeutic conclusions could be drawn from the above findings, to supplement the routine treatment of burns (Tab. 12). The ineluded list will definitely be enlarged, as new results will appear.

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