Conundrum for Psoriasis and Thyroid Involvement

Abstract

Strategies concerning thyroid anomalies in patients confirmed with psoriasis, either on clinical level or molecular levels, and their genetic findings remain an open issue. Identification of the exact subgroup of individuals that are candidates to endocrine assessments is also controversial. Our purpose in this work was to overview clinical and pathogenic data concerning psoriasis and thyroid comorbidities from a dual perspective (dermatologic and endocrine). This was a narrative review of English literature between January 2016 and January 2023. We included clinically relevant, original articles with different levels of statistical evidence published on PubMed. We followed four clusters of conditions: thyroid dysfunction, autoimmunity, thyroid cancer, and subacute thyroiditis. A new piece of information in this field was the fact that psoriasis and autoimmune thyroid diseases (ATD) have been shown to be related to the immune-based side effects of modern anticancer drugs-namely, immune checkpoint inhibitors (ICP). Overall, we identified 16 confirmatory studies, but with heterogeneous data. Psoriatic arthritis had a higher risk of positive antithyroperoxidase antibodies (TPOAb) (25%) compared to cutaneous psoriasis or control. There was an increased risk of thyroid dysfunction versus control, and hypothyroidism was the most frequent type of dysfunction (subclinical rather than clinical), among thyroid anomalies correlated with >2-year disease duration, peripheral > axial and polyarticular involvement. With a few exceptions, there was a female predominance. Hormonal imbalance included, most frequently, low thyroxine (T4) and/or triiodothyronine (T3) with normal thyroid stimulating hormone (TSH), followed by high TSH (only one study had higher total T3). The highest ratio of thyroid involvement concerning dermatologic subtypes was 59% for erythrodermic psoriasis. Most studies found no correlation between thyroid anomalies and psoriasis severity. Statistically significant odds ratios were as follows: hypothyroidism: 1.34-1.38; hyperthyroidism: 1.17-1.32 (fewer studies than hypo); ATD: 1.42-2.05; Hashimoto's thyroiditis (HT): 1.47-2.09; Graves' disease: 1.26-1.38 (fewer studies than HT). A total of 8 studies had inconsistent or no correlations, while the lowest rate of thyroid involvement was 8% (uncontrolled studies). Other data included 3 studies on patients with ATD looking for psoriasis, as well as 1 study on psoriasis and thyroid cancer. ICP was shown to potentially exacerbate prior ATD and psoriasis or to induce them both de novo (5 studies). At the case report level, data showed subacute thyroiditis due to biological medication (ustekinumab, adalimumab, infliximab). Thyroid involvement in patients with psoriasis thus remained puzzling. We observed significant data that confirmed a higher risk of identifying positive antibodies and/or thyroid dysfunction, especially hypothyroidism, in these subjects. Awareness will be necessary to improve overall outcomes. The exact profile of individuals diagnosed with psoriasis who should be screened by the endocrinology team is still a matter of debate, in terms of dermatological subtype, disease duration, activity, and other synchronous (especially autoimmune) conditions.

Keywords: Basedow disease; Hashimoto’s thyroiditis; antibodies; autoimmune; pathogenic; psoriasis; thyroid; thyroid cancer; thyroiditis.

Figure 1

Flowchart of research according to our methodology (please see references below). (Abbreviations: ATD = autoimmune thyroid disease; ICP = immune checkpoint inhibitors).

Figure 2

Potential pathogenic connections or pathologic circumstantial events involving psoriasis and ATD [69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95]. Abbreviations: CH = C hepatitis; APS = autoimmune poly-glandular syndrome; CD = celiac disease; IRF= idiopathic retroperitoneal fibrosis; PBC = primary biliary cholangitis; TS = Turner syndrome; TH = thyroid hormone; PPI= proton pump inhibitors; DPP4is = ipeptidyl peptidase-4 inhibitors; ICP = immune checkpoint inhibitors; JIA = juvenile idiopathic arthritis. Capture of the left: palmar surface involvement due to psoriasis; on the right: thyroid ultrasound with hypoechoic pattern, suggesting thyroiditis.

Figure 3

Qualitative analysis of thyroid involvement in psoriasis, according to our methodology. Abbreviations: TPOAb = antithyroperoxidase antibodies; TgAb = antithyroglobulin antibodies. Central captures: nail psoriasis (subungual hyperkeratosis, nail plate thickening and the “oil drop” sign); bilateral plaques on the lower extremities with thick scales; diffuse scalp involvement.

Figure 4

Analysis of specific psoriasis subtypes and thyroid anomalies according to our methodology (please see references in main text above). References [28,29,34,35,37,38] are pointed out in each box. Abbreviations: EP = erythrodermic psoriasis; PsA = psoriatic arthritis; PsC = cutaneous psoriasis; PP = pustular psoriasis; PV = psoriasis vulgaris; GPP = generalized PP; TPOAb= antithyroperoxidase antibodies; TgAb = antithyroglobulin antibodies; HT = Hashimoto’s thyroiditis.