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Year : 2014  |  Volume : 5  |  Issue : 3  |  Page : 291-295  

Thyroid function tests in cases of polymorphic light eruption: A case-control study

1 Department of Dermatology and Venereology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
2 Department of Endocrinology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India

Date of Web Publication31-Jul-2014

Correspondence Address:
Lata Sharma
Prof. Lata Sharma, Department of Dermatology and Venereology, Institute of Medical Sciences, Banaras Hindu University, Varanasi - 221 005
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2229-5178.137780

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Background: Polymorphic light eruption (PLE) has been found to be associated with thyroid function abnormalities. Aim: To study clinicoepidemiological features of PLE and to study and compare thyroid function tests (TFTs) in cases of PLE. Materials and Methods: The study included 100 cases of PLE and age- and sex-matched controls attending a skin outpatient department. The clinical and epidemiological features were recorded. Both cases and controls were tested for thyroid-stimulating hormone (TSH). In case of abnormality in TSH, triiodothyronine (T3) and tetraiodothyronine (T4) levels were estimated. Results: TFT was abnormal in 25 cases and 7 controls. TSH was elevated in 24 cases and 6 controls and decreased in 1 case and 1 control. T3 and T4 were decreased in 18 cases and 6 controls and elevated in 1 each in case and control. Hypothyroidism was significantly high among cases than controls. Discussion: TFT abnormality was significantly higher among cases than controls. Hypothyroidism has a significant association with PLE. Genetic basis or immune dysfunction may be the cause of both the diseases. PLE may be considered as a clinical presentation of thyroid function disorder and vice versa. Conclusion: Cases of PLE should be examined clinically for thyroid disorder and also tested for TSH or TFT to find any association and prevent serious consequences.

Keywords: Clinical and epidemiological, polymorphic light eruption, tetraiodothyronine, thyroid function tests, thyroid-stimulating hormone, triiodothyronine

How to cite this article:
Sharma L, Lamba S, Singh S K. Thyroid function tests in cases of polymorphic light eruption: A case-control study . Indian Dermatol Online J 2014;5:291-5

How to cite this URL:
Sharma L, Lamba S, Singh S K. Thyroid function tests in cases of polymorphic light eruption: A case-control study . Indian Dermatol Online J [serial online] 2014 [cited 2021 Sep 16];5:291-5. Available from: https://www.idoj.in/text.asp?2014/5/3/291/137780

   Introduction Top

Solar radiation is beneficial and essential for life, but some people develop allergic cutaneous response to sunlight known as polymorphic light eruption (PLE). [1],[2] Thyroid function abnormalities have been found to occur in patients with sunlight-associated dermatoses such as melasma and PLE. [3],[4],[5] Therefore, a comparative study of thyroid function tests (TFTs) was carried out among 100 cases of PLE with equal number of controls. The clinicoepidemiological features of PLE were also noted to find its relation with TFT.

   Materials and methods Top

The study included 100 cases of PLE and equal number of age- and sex-matched controls attending the skin outpatient department at S. S. Hospital from February 2010 to June 2011. After obtaining informed witnessed consent of the patients, thyroid functions were studied. The study was approved by the institutional review board and ethics committee.

The inclusion criterion of patients was clinical diagnosis of PLE. The exclusion criteria were pregnancy, lupus erythematosus, inflammatory photodermatoses, and use of systemic or topical steroid or drugs causing photosensitivity such as quinolones, tetracyclines, sulfonamides, antimalarials, phenothiazines, or specific treatment for PLE in the previous three months.

Complaints of patients were noted on a proforma such as the rash on exposure to sunlight, artificial light, or heat, and whether transient or persistent. Associated sensations of itching, burning, or pain along with swelling, oozing, discharge, and fever were recorded. The month of onset of rash, seasonal variation, treatment taken, discoloration, or scarring on healing were noted.

Symptoms of thyroid disorder such as irritability, nervousness, depression, pain, aches, tiredness, fatigue, apathy, change in weight, heat or cold intolerance, dyspnea on exertion, diarrhea, constipation, hoarseness or slurring of voice, vision defects, lacrimation, pain or redness in eyes, and effect of stress was noted including menstrual history in females. History of similar illness in the past and in the family was also recorded.

Clinical examination of all cases and controls was done in a similar way. The palpable thyroid gland was graded as per the five-point scale designed by Lewinski in 2002 (grade 0: no goiter present, thyroid impalpable and invisible; grade 1a: thyroid gland, however palpable, remains invisible, even in full extension of the neck, thyroid not enlarged; grade 1b: goiter palpable in normal position and visible in the upright position, full extension of the neck; nodular goiters are also classified into this size range, even if they do not meet the criteria of enlarged thyroid gland; grade 2: goiter visible in normal position of the neck, no palpation required to diagnose thyroid enlargement; grade 3: very large goiter, clearly visible from a distance).

Mucocutaneous examination was done in PLE cases noting skin type as classified on a six-point scale designed by Wolff in 1977. Distribution and type of lesions with secondary changes and lesions of associated diseases were recorded. In case of doubt in diagnosis, the patients were asked to avoid sunlight exposure by covering the exposed parts for 15 days and were re-examined.

A blood sample (5 mL) was taken from each case and control for the estimation of serum thyroid-stimulating hormone (TSH) levels in the endocrinology laboratory. If serum TSH (0.5-5.0 μIU/mL, normal range) level was found abnormal, further investigations for the estimation of serum triiodothyronine (T3) and thyroxine (T4) were done by Immunotech kit. The parameters studied during the observation period were compared using student's t0-test for parametric variables and Chi-square test for nonparametric variables. For comparison of the probability, P < 0.05 was taken as significant difference.

   Results Top

There were 60 females and 40 males each in both cases and controls. The age of cases and controls varied from 5 to 60 years, the mean being 30.01 + 8.89 and 30.5 + 7.79 years, respectively. About two-thirds of the patients were in the age group of 21 to 40 years. Age of the patients did not correlate significantly with TFT abnormality [Table 1]. The ratio of males and females was 3 : 2 [Table 2].
Table 1: TFT and age of cases and controls

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Table 2: TFT and sex of PLE cases and controls

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The number of housewives, students, service people, farmers, and business in cases were 45, 22, 18, 12, and 3, and in controls 40, 30, 15, 9, and 6, respectively. The number of patients belonging to Uttar Pradesh, Bihar, and Madhya Pradesh in cases were 81, 14, and 5 and in controls 75, 21, and 4, respectively (residence and abnormal TFT χ2 3.063; P = 0.216).

There were 24, 17, 23, 22, and 14 PLE cases with duration in days ranging from 0 to 20, 21 to 40, 41 to 60, 61 to 80, and 81 to 100 days, respectively (χ2 = 0.189; P > 0.9). The month of onset of the disease was March, April, September, and October in 10, 12, 12, and 21 (55%) cases, respectively (χ2 = 2.61; P > 0.4).

Skin rash was present in all the cases. There were complains of a sensation of itching in 75, burning in 10, and both in 5 cases at the site of lesions. There was fever with malaise in two; headache and swelling of face in one case each. Fifty-eight cases presented during the first episode of PLE, whereas 24 had a recurrence ( P > 0.7). There was a history of atopy in nine cases. Family history of PLE was present in 10 and atopy in 15 cases ( P > 0.9).

Clinical features of thyroid disorder and swelling with abnormal TFT were present in 20 cases and 4 controls [Figure 1], [Figure 2], [Figure 3], [Figure 4]. Bradycardia was noted in 15 cases and tachycardia in 3. Dry skin, lusterless hair, purplish lip, malar flush, and increased sweating was observed in three cases and one control ( P > 0.5). One case and one control had exophthalmia ( P > 0.6, [Figure 5] and [Figure 6]). The cutaneous features of thyroid disorders in the case group and control group was compared, and the difference was found to be statistically insignificant ( P = 0.4). The ocular features of thyroid disorders in cases and controls were also compared, and it was found that no significant statistical difference was present ( P = 0.6). Three cases had pedal edema, four melasma, and two vitiligo (females, TFT abnormal). Fasting and postprandial blood sugar tests were done in 10 cases because of a doubt of diabetes, but no abnormality was detected.
Figure 1: Polymorphic light eruption over the forehead with goiter in 48– year-old

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Figure 2: Polymorphic light eruption papules over the back of patient in Figure 1

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Figure 3: Polymorphic light eruption with goiter

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Figure 4: Polymorphic light eruption with hypopigmented macules in same patient as in Figure 3

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Figure 5: Polymorphic light eruption with exophthalmia in 42-year-old male

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Figure 6: Polymorphic light eruption in same patient as in Figure 5

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The skin was of type III in 7, IV in 75, V in 16, and VI in 2 cases (χ2 = 0.98; P > 0.9). Multiple sites involved in PLE were upper limbs in 64, neck in 63, face 22, back 6, legs 2, and abdomen in 1 case [Table 3]. The lesions were of single type as papules, plaques, and macules in 27, 16, and 16 cases, respectively, and mixed type as papules with plaques, papules with vesicles, and papules with macules in 26, 8, and 7 cases, respectively (χ2 = 0.126 P > 0.9). The lesions were erythematous in 20, hyperpigmented in 19, skin colored in 10, and hypopigmented in 8 cases. The color of lesions were erythematous or hyperpigmented; skin colored or hyperpigmented; skin colored or erythematous; and hyperpigmented or hypopigmented in 30, 5, 5, and 3 cases, respectively (χ2 = 8.54; P > 0.6).
Table 3: Abnormal TFT and site of PLE in cases

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TFT was abnormal in 25 cases and 7 controls; hypothyroidism was present in 24 cases and 6 controls and hyperthyroidism in 1 case and 1 control; hypothyroidism was significantly higher in cases than controls. The clinical and epidemiological features of PLE such as age, gender, occupation, place of residence, duration of PLE, month of onset, site of lesion, history of recurrence, family history, type of skin, type of lesion, and color of the lesion were not found related to abnormal TFT on statistical comparison. μIU/ml was high in 24 cases (5.7 to 10.2 μIU/mL) and 6 controls (0.4 to 8.2 μIU/mL). T3 was low in 18 cases (25 to 56 ng/dL) and 5 controls (30 to 210 nag/dl), T4 was also low in 18 cases (2.3 to 14 μg/dl) and 5 controls (2.4 to 13 μg/dl) and was significant [Table 4].
Table 4: TFT in cases and controls

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   Discussion Top

The present study was conducted at Varanasi, Uttar Pradesh, India (25° N and 83° E) where prevalence was found to be 0.56% in a previous study. [2] TFT abnormality was significantly high in cases than controls [Table 4]. Seetharam and Sridevi conducted a study in Guntur, Hyderabad situated in south India, relatively nearer the equator than Varanasi, and reported hypothyroidism in 29 out of 112 (25.9%) cases and 3 out of 40 controls (7.5%). [4] Kochupillai suggested a significant relation between PLE and thyroid disease rather than a mere coincidence. [6]

In the present study, 10% male and 35% female cases and in controls 5% males and 8.33% females had abnormal TFT, but the difference was not significant [Table 2]. There was hypothyroidism in 11 out of 94 (11.7%) female cases in the study of Hasan et al.[5] They reported that PLE is a long-standing, slowly ameliorating disease with some tendency to development of autoimmune disease or thyroid disorder, especially in female patients. Seetharam and Sridevi found 27 female cases (31.3%) and 3 female controls out of 112 cases and 40 controls. They said that probably the relation between the two diseases is immune dysfunction causing hypersensitivity reaction as PLE, and antibody generation leading to thyroid disease. [4] In the present study, the prevalence in females was found to be much higher (35%), possibly due to better sensitivity of radioimmunoassay tests, but this was statistically not significant. There was no difference in PLE lesions between cases having normal and abnormal TFT; so, it was not possible to predict the cases of PLE likely to have a thyroid disorder until a clinical examination of the thyroid gland was done and specific features of thyroid involvement were discussed.

Ultraviolet radiation is known to cause less immunosuppression in patients of PLE than controls, and inheritance of PLE is polygenic or due to a dominant single gene. [8],[9] Mimouni et al. have reported three generations of a family as first evidence of an autosomal dominant mode of transmission of TSH unresponsiveness, which they suggested may enable identification of the precise defect by a genetic linkage study.

   Conclusion Top

The association of both the diseases may be immune dysfunction or genetic in origin. PLE may be a clinical presentation of thyroid function disorders and vice versa. PLE patients are prone to have thyroid disorders; therefore, all cases of PLE need to be clinically examined for features of thyroid disorder and investigated for TSH or TFT to prevent serious consequences.

   References Top

1.Sharma L. Beneficial and therapeutic effects of terrestrial solar radiation.Indian Medical Gazette 2008;142:244-6.  Back to cited text no. 1
2.Sharma L, Basnet A. A Clinicoepidemiological study of polymorphic light eruption. Ind J Dermatol Venereol Leprol 2008;74:15-7.  Back to cited text no. 2
3.Sharma L, Kumar P, Agrawal JK. Study of thyroid function and microsomal antibodies in cases of melasma. Quat J Surg Sci 1999;35:13-20.  Back to cited text no. 3
4.Seetharam KA, Sridevi K. Association of polymorphic light eruption and autoimmune thyroiditis. Indian J Dermatol Venereol Leprol 2010;76:704-5.  Back to cited text no. 4
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5.Hasan T, Ranki A, Jansen CT. Disease association in polymorphic light eruption. A long term follow up of 94 patients. Arch Dermatol 1998;134:1081-5.  Back to cited text no. 5
6.Kochupillai N. Clinical endocrinology in India. Curr Sci 2000;79:1061-7.  Back to cited text no. 6
7.Palmer RA. Fredman PS. Ultraviolet radiation causes less immunosuppression in patients with polymorphic light eruption than in controls. J Invest Dermatol 2004;122:291-4.  Back to cited text no. 7
8.Millard Bataille V, Snieder H, Spector TD, McGregor JM. The heritability of polymorphic light eruption. J Invest Dermatol 2000;115:467-70.  Back to cited text no. 8
9.Mimouni M, Mimouni Bloch A, Sachachter J, Shohat M. Familial hypothyroidism with autosomal dominant inheritance. Arch Dis Child 1996;75:245-6.  Back to cited text no. 9


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]

  [Table 1], [Table 2], [Table 3], [Table 4]


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