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Year : 2004  |  Volume : 70  |  Issue : 6  |  Page : 353-356

The effect of thyroid hormones in psoriasis vulgaris

Departments of Dermatology, Kahramanmaras Sutcuimam University, Kahramanmaras, Turkey

Correspondence Address:
Sehit Abdullah Cavus M. Alparslan Turkes Bulvari Gulsaray A. B Blok K:3 D:6 Kahramanmaras, Turkey
[email protected]


BACKGROUND AND AIMS: Certain endocrinological disturbances are assumed to exacerbate psoriasis. In this study we compared the serum thyroid hormone levels of a group of psoriasis patients with that of a control group. METHODS: The total T3 (TT3), free T3 (FT3), total T4 (TT4), free T4 (FT4) and TSH levels obtained from the sera of 103 psoriatics (37 males and 66 females) and 96 controls (40 male and 56 female) were measured by immunological assay. RESULTS: Statistical assessments displayed no differences in TT3, FT4 and TSH serum levels for the two groups. Differences between the means of serum TT4 (P=0.033) and serum FT3 (P=0.041) levels showed statistical differences among the groups. We also found that at least one thyroid hormone level in the blood was increased in 23 patients of the psoriatic group compared to 9 patients in the control group (P=0.022). The average Psoriasis Area and Severity Index scores in this patient group were significantly higher than in those with normal hormone levels (P<0.001). CONCLUSIONS: The role of thyroid hormones in the etiopathogenesis of psoriasis and the effects of such differences in psoriatic patients must be investigated with wider and comprehensive laboratory and clinical studies.

How to cite this article:
Arican O, Bilgic K, Koc K. The effect of thyroid hormones in psoriasis vulgaris. Indian J Dermatol Venereol Leprol 2004;70:353-6

How to cite this URL:
Arican O, Bilgic K, Koc K. The effect of thyroid hormones in psoriasis vulgaris. Indian J Dermatol Venereol Leprol [serial online] 2004 [cited 2021 Jan 22];70:353-6. Available from:

   Introduction Top

Psoriasis is a common, chronic relapsing skin disease.[1] Certain endocrinological disturbances exacerbate the disease.[2] An improvement in psoriasis was reported in a psoriatic with hyperthyroidism.[3] It was shown that two thyroid hormones, T3 and T4, cause an increase in Epidermal Growth Factor (EGF) which leads to epidermal hyperplasia.[4] In two different studies Safet et al reported that T3 stimulates the proliferation of keratinocytes.[5],[6]

We compared the levels of thyroid hormones a group of patients with psoriasis vulgaris with those of a control group. We also correlated the PASI (Psoriasis Area and Severity Index) scores in the psoriasis group with serum levels of thyroid hormones.

   Methods Top

Consecutive patients with psoriasis who had not received any prior treatment within one month were included in the study. Exclusion criteria were psoriatics or controls with known thyroid impairment; those on thyroid hormone, anti-thyroid drugs or other drugs affecting thyroid function, such as lithium, iodine, steroids, dopamine, anticonvulsant drugs, and interferon (which interferes with thyroid hormone level estimation); those who have undergone thyroidectomy; pregnant women and children aged less than 12 years. Patients with erythrodermic, pustular and only palmoplantar forms of psoriasis were also excluded. The control group was comprised of randomly selected patients from our clinic having skin diseases other than psoriasis.

Blood samples were collected on empty stomach between 08:30-10:30 hours. Measurements were carried out by using total T3 (TT3), free T3 (FT3), total T4 (TT4), free T4 (FT4) and TSH (Thyroid Stimulating Hormone) Immulite 2000 kits with the aid of an immunometric assay method. The severity of psoriasis was assessed by the PASI score for each patient.

Statistical assessment was done by using the SPSS 10.0 for Windows. Unpaired t-test was used when comparing mean values between groups. Chi-square test was used when comparing differences between the frequencies. A significance level of P Value < 0.05 was chosen.

   Results Top

A total number of 103 psoriatics (37 males and 66 females), and 96 controls (40 males and 56 females) were included in the study. The age of patients in the psoriasis group ranged from 16 to 79 (mean: 38.03 21.48) years and 14 to 90 (mean: 34.16 19.66) years in the control group. There was no statistical difference between the groups in terms of sex (P=0.406) and distribution of age (P=0.184). The duration of disease in the patient group ranged from 1 month to 65 years (mean: 11.02 13.18 years).

The serum values of different thyroid hormones of both groups are shown in [Table - 1]. On comparing both groups, the mean values of only FT3 and TT4 show a statistically significant difference (P<0.05). At least one thyroid hormone level in blood was increased in 23 (22.33%) patients of the psoriatic group as compared to 9 (9.37%) patients in the control group (P=0.022). The average PASI score in those 23 patients [10.99 5.01 (4.9-22.5)] was relatively higher than that of patients in the psoriatic group having normal hormone levels [6.24 3.46 (1.4-15.5)]. This difference in the average PASI scores between those two groups was statistically significant (P<0.001).

   Discussion Top

In spite of the fact that many developments are recorded in the treatment and pathogenesis of psoriasis, its etiology still remains obscure. Propylthiouracil, an anti-thyroid preparation, was successfully used both in local[7] and systemic[8],[9],[10] treatment of psoriasis. Although the mechanism of action was unclear, it was suggested that this drug might have a regulatory effect on the T cells in the psoriasis plaque.[9],[10] Propylthiouracil increased the number of total and suppressor/cytotoxic T cells and reduced activated lymphocytes in psoriatic plaques.[10] Other anti-thyroid agents, such as methimazole[11] and thiamazole,[12] have also been used successfully in the treatment of psoriasis. This means that thyroid hormones may have unknown effects on the disease.

It is postulated that T3 receptors may play a role in the synthesis of keratin.[8] The existence of T3 receptors on the skin was also proved.[13] Propylthiouracil, which is known to be an anti-thyroid drug, may affect the keratin synthesis process by binding to nuclear T3 receptors.[14] It is also known that T3 has a major role in the regulation of cell growth and differentiation.[15],[16] Moreover, it has been stated that T3 and T4 have hyperproliferative effect on the skin by EGF.[4]

In this study the serum TT4 and FT3 levels were significantly higher in psoriatics than in the control group. The average PASI scores were significantly higher in these patients and this may be due to the direct or indirect effects of thyroid hormones on the course of psoriasis. Thus excessive production of thyroid hormones may aggravate psoriasis.

The skin may be a target organ for thyroid hormones and these hormones increase EGF and therefore accelerate epidermal proliferation.[5],[17] The role of these hormones on the etiopathogenesis of psoriasis will become clearer when the effect of thyroid hormones on keratinocytes and the anti-proliferative effect of anti-thyroid drugs on psoriasis are better demonstrated with experimental studies. Meanwhile, it may be useful to check the thyroid function in patients with uncontrolled and relapsing psoriasis. 

   References Top

1.Cristophers E, Mrowietz U. Psoriasis. In: Freedberg IM, Eisen AZ, Wolff K, Austen KF, Goldsmith LA, Katz SI, et al, editors. Fitzpatrick's Dermatology in General Medicine, 5th Ed. New York: McGraw-Hill; 1999. p. 495-521.  Back to cited text no. 1    
2.Tagami H. Triggering factors. Clin Derm 1997;15:677-85.  Back to cited text no. 2  [PUBMED]  [FULLTEXT]
3.Humphreys MS, Waddell JL. Lithium, psoriasis, abnormal glucose tolerance and thyroid dysfunction. Br J Psychiatry 1988;152:437-8.  Back to cited text no. 3  [PUBMED]  
4.Hoath SB, Lakshmanan J, Scott SM, Fisher DA. Effect of thyroid hormones on epidermal growth factor concentration in neonatal mouse skin. Endocrinology 1983;112:308-14.  Back to cited text no. 4  [PUBMED]  
5.Safer JD, Fraser LM, Ray S, Holick MF. Topical triiodothyronine stimulates epidermal proliferation, dermal thickening, and hair growth in mice and rats. Thyroid 2001;11:717-24.  Back to cited text no. 5  [PUBMED]  [FULLTEXT]
6.Safer JD, Crawford TM, Fraser LM, Hoa M, Ray S, Chen TC, et al. Thyroid hormone action on skin: Diverging effects of topical versus intraperitoneal administration. Thyroid 2003;13:159-65.  Back to cited text no. 6  [PUBMED]  [FULLTEXT]
7.Elias AN, Dangaran K, Barr J, Rohan K, Goodman MM. A controlled trial of topical propylthiouracil in the treatment of patients with psoriasis. J Am Acad Dermatol 1994;31:455-8.  Back to cited text no. 7    
8.Elias AR, Barr RJ. Low dose oral propylthiouracil in the treatment of plaque psoriasis. Int J Dermatol 1995;34:519-20.  Back to cited text no. 8  [PUBMED]  
9.Elias AN, Goodman MM, Liem WH, Barr J. Propylthiouracil in psoriasis: Result of an open trial. J Am Acad Dermatol 1993;29:78-81.  Back to cited text no. 9    
10.Chowdhury MM, Marks R. Oral propylthiouracil for the treatment of resistant plaque psoriasis. J Dermatol Treat 2001;12:81-5.  Back to cited text no. 10  [PUBMED]  [FULLTEXT]
11.Elias AN, Goodman MM, Rohan MK, Alpern K, Barr RJ. Methimazole in psoriasis: Results of an open trial. Dermatology 1993;187:26-9.  Back to cited text no. 11  [PUBMED]  
12.Abe M, Ohnishi K, Hasegawa M, Aoyama K, Tamura A, Kan C, et al. The antipsoriatic effect of thiamazole is not accompanied either by significant changes in blood lymphocyte subsets nor by serum concentration of TNF-alpha. Eur J Dermatol 2002;12:335-9.  Back to cited text no. 12  [PUBMED]  [FULLTEXT]
13.Ribeiro RC, Apriletti JW, West BL, Wagner RL, Fletterick RJ, Schaufele F, et al. The molecular biology of thyroid hormone action. Ann N Y Acad Sci 1995;758:366-89.  Back to cited text no. 13  [PUBMED]  
14.Takagi S, Hummel BC, Walfish PG. Thionamides and arsenite inhibit T[3] binding to hepatic nuclear receptor. Biochem Cell Biol 1990;68:616-21.  Back to cited text no. 14  [PUBMED]  
15.Wagner RL, Apriletti JW, McGrath ME, West BL, Baxter JD, Fletterick RJ. A structural role for hormone in the thyroid hormone receptor. Nature 1995;378:690-7.  Back to cited text no. 15  [PUBMED]  [FULLTEXT]
16.Torma H, Rollman O, Vahlquist A. Detection of mRNA transcripts for retinoic acid, vitamin D3, and thyroid hormone (c-erb-A) nuclear receptors in human skin using reverse transcription and polymerase chain reaction. Acta Derm Venereol 1993;73:102-7.  Back to cited text no. 16  [PUBMED]  
17.Hoath SB, Lakshmanan J, Fisher DA. Epidermal growth factor binding to neonatal mouse skin explants and membrane preparations - effect of triiodothyronine. Pediatr Res 1985;19:277-81.  Back to cited text no. 17  [PUBMED]  


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