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Correlations among insulin-like growth factor-1, homocysteine, vitamin B12, and folic acid plasma levels following isotretinoin therapy in acne vulgaris patients

Yosef, Aymana,c; Dawoud, Noha M.b; Gharib, Khaleda

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Journal of the Egyptian Women’s Dermatologic Society: January 2018 - Volume 15 - Issue 1 - p 47-53
doi: 10.1097/01.EWX.0000529795.14438.c1
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Oral isotretinoin (13-cis-retinoic-acid) is a highly effective treatment agent for moderate to severe acne, when resistant to conventional therapy 1. However, it has multiple side effects including mucocutaneous, musculoskeletal, ophthalmic, central nervous systems, and some metabolic side effects such as dyslipidemia 2. Treatment also leads to neuropsychiatric side effects such as depression, psychotic symptoms, and suicidal attempts 3. Drug-regulatory agencies worldwide are warning isotretinoin-treated patients of the risk of potential psychiatric side effects 4.

Growth factors in the brain are related to depression and its treatment. Feily and Namazi 5 reported a decrease in insulin-like growth factor-1 (IGF-1) expression by isotretinoin and suggested that this can explain triggering of depression in some patients taking this medication. In addition, isotretinoin may also affect cystathionine-β-synthase, the enzyme responsible for homocysteine (Hcy) metabolism in the liver, and may lead to hyperhomocysteinemia. Hcy is recycled into methionine by a transmethylation reaction requiring vitamin B12 and folate. Any deficiency in these cofactors results in hyperhomocysteinemia 6. This hyperhomocysteinemia, as an isotretinoin side effect, might contribute toward the missing link between isotretinoin and neuropsychiatric disorders 7.

In the current study, we aimed to investigate the plasma Hcy level, the cofactors involved in its metabolism (vitamin B12 and folic acid), and IGF-1 levels in patients receiving isotretinoin treatment for acne vulgaris and to correlate those biochemical parameters with each other and with the demographic data of patients and their clinical response.

Patients and methods

This case series study was carried out on 60 patients with moderate to severe acne vulgaris. Patients were recruited from the dermatology clinic, Future Hospital, Jeddah, Kingdom of Saudi Arabia. The written consent form was approved by the local research and ethical committee, and was signed by every patient included in the study. The study was carried out in accordance with the Helsinki Declaration 2008.

Inclusion criteria

Selected patients were either men, nonpregnant women older than 18 years of age, or women using at least two safe methods of contraception and suffering from moderate to severe acne vulgaris.

Exclusion criteria

Patients using vitamin A supplements or any multivitamin preparations; patients with a history of diseases affecting vitamin B12 and/or folic acid metabolism (pernicious or megaloblastic anemia, malabsorption syndromes); or using drugs affecting their metabolism within the previous 3 months (phenytoin, cyclosporin, methotrexate); thyroid dysfunction; and previously known diabetes mellitus or familial hypercholesterolemia were excluded from the study. Patients with any disease that affected growth hormone (GH) and any severe or chronic systemic disorders were also excluded.

Clinical assessment

Baseline assessment was performed and the severity of acne was recorded using the global acne grading system (GAGS) score, which ranges between 1 and 39 8. Patients were treated with isotretinoin (0.4–0.6 mg/kg/day) in two divided doses after meals for 4 consecutive months. Screening for hormonal and biochemical parameters was performed just before initiation (baseline) and after 4 months of isotretinoin treatment (post-treatment). These parameters included IGF-1, Hcy, folic acid, and vitamin B12. Hemoglobin, creatinine, serum glutamic-oxaloacetic transaminase (SGOT), serum glutamic-pyruvic transaminase (SGPT), total cholesterol (TC), triglycerides (TGs), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and very low-density lipoprotein cholesterol (VLDL-C) were also determined to follow isotretinoin therapy as a routine.

After 4 months of isotretinoin treatment, the cumulative dose of isotretinoin was calculated and patients were reassessed for their acne severity. Clinical response was recorded as ‘Responding’ when cured or improved and ‘nonresponding’ when not improved or worsened.

Sample collection and biochemical analysis

Fasting blood samples were obtained by venepuncture after a 12 h fast. The samples were then centrifuged immediately; the plasma was separated and stored at −80°C. To avoid variation, all samples were studied on the same day and using the same kit.

Fasting serum TC, TGs, LDL-C, HDL-C, SGOT, and SGPT concentrations were measured enzymatically using an automatic analyzer (Konelab 60i; Thermo Fisher Scientific Inc., Waltham, Massachusetts, USA). VLDL concentrations were calculated using the Friedewald equation. Full blood count was performed using an automated Coulter_LH 780 Hematology Analyzer (Beckman Coulter Inc., Brea, California, USA). IGF-1 levels were determined in one run using a two-site, solid-phase, chemiluminescent immunometric assay (Immulite 1000; Diagnostic Products Corp., Los Angeles, California, USA), using murine monoclonal anti-IGF-1 antibodies. Serum folic acid and vitamin B12 were analyzed using a chemiluminescence immunoassay (Roche Elecsys 2010; Roche Diagnostic Corporation, Indianapolis, Indiana, USA). Plasma Hcy levels were measured using an Abbott AxSYM assay (Abbott Laboratories, Medical Diagnostics Products, New Jersey, USA).

Statistical analysis

Data were collected, tabulated, and analyzed statistically using the statistical package for the social sciences version 20.0 (IBM Corporation; Armonk, New York, USA). Qualitative data were represented as number and percentage, whereas quantitative data were represented as mean±SD. Differences were tested between two independent parametric groups using a t-test, paired by paired t, and correlated by Pearson’s correlation. The P value was set at less than 0.05 for significant results.


Sixty patients with acne vulgaris were included in the study (23 men and 37 women), with a male to female ratio of 1 : 1.6. The minimum age of the patients was 18 years and the maximum age was 40 years, with a mean age of 27.78±6.33 years. The mean duration of disease was 4.82±1.77, ranging between 2 and 10 years. Fifty-one (85%) patients responded to isotretinoin treatment, whereas nine (15%) patients did not respond to isotretinoin treatment.

Baseline and post-treatment levels of biochemical parameters

The IGF-1, vitamin B12, and folic acid levels were significantly lower in the post-treatment assessment compared with the baseline levels, whereas isotretinoin treatment post-treatment plasma Hcy level was significantly higher compared with the baseline level (Table 1).

Table 1
Table 1:
Baseline and postisotretinoin treatment values of some biochemical parameters

With respect to the lipid profile, post-treatment TC, TGs, and VLDL-C were significantly higher compared with the baseline levels, whereas serum LDL-C and HDL-C were not significantly affected by isotretinoin treatment. Post-treatment SGPT values were significantly higher than the baseline values, whereas no difference was detected between post-treatment and baseline SGOT or hemoglobin values (Table 1).

Correlations between the age of patients, global acne grading system score, and each of the baseline and post-treatment values of insulin-like growth factor-1, homocysteine, folic acid, and vitamin B12

IGF-1 values after isotretinoin treatment tended to correlate negatively with the age of the patients (P=0.06), whereas vitamin B12 showed a significant positive correlation with their age (P=0.03). No significant correlation was detected between each of the baseline and post-treatment values of folic acid, Hcy, and the age of the patients (Table 2).

Table 2
Table 2:
Correlations between the age of the patients, global acne grading system score, and each of the baseline and post-treatment values of insulin-like growth factor-1, homocysteine, folic acid, and vitamin B12

In addition, the baseline GAGS score showed a significant positive correlation with post-treatment IGF-1 (P=0.03) (Table 2).

Differences between both sexes in insulin-like growth factor-1, homocysteine, folic acid, and vitamin B12 values

Hcy level was significantly higher in men compared with women at baseline (P=0.02); however, no significant differences were found between both sexes in the post-treatment values of all other measured parameters (Table 3).

Table 3
Table 3:
Differences between both sexes in insulin-like growth factor-1, homocysteine, folic acid, and vitamin B12 values

Clinical response of the treated patients in relation to the measured parameters

The mean post-treatment Hcy value was significantly lower in responding (13.91±1.97) compared with nonresponding (15.40±1.41) patients (P=0.03). Also, the post-treatment IGF-1 mean value was significantly lower in responding (130.88±41.54) than in nonresponding (173.44±87.66) patients (P=0.02). However, no differences were found in the mean values of vitamin B12 and folic acid in relation to patients’ response (Fig. 1).

Figure 1
Figure 1:
Clinical response of the treated patients in relation to the post-treatment mean values of the measured parameters. Hcy, homocysteine; IGF-1, insulin-like growth factor-1.

Correlations between post-treatment and baseline insulin-like growth factor-1, homocysteine, folic acid, and vitamin B12 mean values

There was a highly significant positive correlation between post-treatment and baseline values of IGF-1 and also folic acid (P<0.001 for both) (Table 4). Baseline values of IGF-1 and Hcy were correlated negatively (P=0.001) (Fig. 2a). Also, there was a significant negative correlation between post-treatment IGF-1 and baseline Hcy mean values (P=0.002) (Table 4, Fig. 2b).

Table 4
Table 4:
Correlations between post-treatment and baseline values of insulin-like growth factor-1, homocysteine, folic acid, and vitamin B12
Figure 2
Figure 2:
Correlation between (a) baseline Hcy and IGF-1 (b) baseline homocysteine (Hcy) and post-treatment insulin-like growth factor-1 (IGF-1).

Correlations between the cumulative dose of isotretinoin, changes in liver enzymes, and post-treatment values of the measured parameters

Post-treatment values of vitamin B12 showed a significant positive correlation with the cumulative dose of isotretinoin (P=0.05). However, other measured parameters (folic acid, IGF-1, and Hcy) were not correlated with its cumulative dose (P>0.05). Moreover, the plasma levels of IGF-1 and Hcy following isotretinoin therapy were not correlated with the recorded changes in liver enzymes (P>0.05) (Table 5).

Table 5
Table 5:
Correlations between cumulative dose of isotretinoin, changes in liver enzymes, and post-treatment values of the measured parameters


Isotretinoin, a vitamin A derivative, has many side effects. Some of these side effects such as arthralgia and depression are similar to those observed in GH deficiency. There are very few studies investigating the effect of isotretinoin on GH 9. As GH is secreted in pulsatile manner, we should not rely on random GH measurements for the diagnosis of GH deficiency. Thus, serum IGF-1 and insulin-like growth factor-binding protein 3 (IGFBP3), which are GH-dependent markers, are used for the diagnosis of GH deficiency. Serum IGF-1 level is more sensitive than IGFBP3, which responds less markedly to the same dose of GH 10. Thus, in the present study, we used IGF-1 as a marker for GH activity and we found it to be significantly decreased with 4 months of isotretinoin treatment. This was in agreement with Karadag et al.9, who observed a significant decrease in IGF-1 and IGFBP3 levels after 3 months of treatment with isotretinoin, with no significant difference in the GH level.

Some studies have shown a relationship between IGF-1 and sebum secretion. IGF-1 level increases during adolescence with the appearance of acne in many patients 11. IGF-1 enhances the expression of sterol response element-binding protein-1, which stimulates lipogenesis in sebocytes 12. The decrease in IGF-1 with isotretinoin therapy may be one of the mechanisms to act as an antiandrogen and antiacne. This was proved in the current study by the lower mean values of IGF-1 in responding compared with nonresponding patients. Also, the decrement decrease IGF-1, being one of the growth factors in the brain, and when administered to mice, shows an anti-depressant-induced behavior, and could explain triggering of depression in some patients using isotretinoin 5.

Although there was no correlation between the baseline IGF-1 level and patients’ age, there was a tendency of post-treatment IGF-1 level to correlate negatively with age. Thus, we suggest that older patients could have a higher risk of being susceptible to IGF-1 deficiency following isotretinoin therapy with increased incidence of its related side effects and also increased isotretinoin efficacy. However, further studies with larger numbers of patients are required to study this.

Post-treatment IGF-1 was correlated positively with the baseline GAGS score and this may explain the decreased efficacy of isotretinoin in more severe acne grades and the need for more prolonged treatment and sometimes repetition of the treatment course.

The liver is the major organ for the metabolism of Hcy and the production of IGF-1. Hcy metabolism and IGF-1 synthesis may be impaired in chronic liver diseases 13. Isotretinoin is a major cause of liver dysfunction 7. That was evident in the present study with the elevated SGPT values after treatment. Thus, impaired liver function might be the main cause of hyperhomocysteinemia and IGF-1 deficiency following isotretinoin therapy. However, there was no correlation between their levels and the mean post-treatment liver enzyme values. This needs to be confirmed with further studies.

Previous studies on patients of different age groups observed an apparent association of hyperhomocysteinemia with decreased IGF-1 13–15. Hcy level is found to be higher in men than in women 16 and this is in agreement with our results at baseline; however, post-treatment values were not affected by sex differences.

The current study proved that hyperhomocysteinemia and the deficiency of both folic acid and vitamin B12 occurred following isotretinoin therapy, which was reported by several previous studies 7,17,18. Moreover, in a previous study 19, only 30 days of treatment with isotretinoin was enough to cause folic acid deficiency. In the present study, longer duration (4 months) of isotretinoin treatment was associated with increased mean values of Hcy and decreased mean values of folic acid and vitamin B12 compared with the baseline values. The enzyme Hcy methyltransferase requires vitamin B12 and folic acid as cofactors, and any deficiency in either of them may result in hyperhomocysteinemia 20. However, in the present study, there was no correlation between post-treatment mean values of Hcy and neither vitamin B12 nor folic acid baseline or post-treatment mean values. Thus, we can suggest that hyperhomocysteinemia following isotretinoin therapy may be because of liver dysfunction and/or inhibition of the enzyme required for the metabolism of Hcy by the drug in a way that is not completely dependent on either vitamin B12 or folic acid. The plasma level of Hcy has frequently been noted to be inversely varied with that of folate, vitamin B12, or vitamin B621. However, in isotretinoin-treated patients, no similar correlation has been observed, suggesting a B-vitamin-independent disturbance of Hcy homeostasis 18, and this underscores our findings.

Therefore, clinical trials should be conducted aiming to clarify whether vitamin B12 and folic acid supplementation with initiation of isotretinoin treatment could be useful for preventing hyperhomocysteinemia and its associated side effects or not. However, it has been reported that various vitamin supplements, most prominently vitamin B12, could exacerbate existing acne and/or lead to the development of acneiform eruptions 22. Thus, contrary opinions on the need for vitamin supplements in patients on isotretinoin treatment have been proposed 7. Gökalp et al.23 suggested that vitamin B12/folic acid should be administered before and during isotretinoin therapy under medical supervision and their supplementation should be prescribed only when deficient.

In addition to the disturbed lipid profile following isotretinoin therapy, hyperhomocysteinemia was reported to be a major risk for ischemic heart disease 24,25 and might be linked to dementia 26. Folic acid deficiency is associated with neuropathy, psychiatric disorders, cognitive dysfunction, dementia, megaloblastic anemia, congestive heart failure, pigmentation, and infertility 27.

It is known that vitamin B12 deficiency is associated with an increased incidence of depression and other neuropsychiatric disorders 28. In the current study, vitamin B12 serum values were affected significantly by isotretinoin treatment, particularly in younger patients, as evident from the significant positive correlation between post-treatment vitamin B12 values and the age of the patients. In previous studies, the incidence of vitamin B12 deficiency was significantly higher in the 21–40 and 41–60-year age groups compared with the more than 60-year group of Indian patients 29. Also, the National Health and Nutrition Survey (Ensanut) 2012 reported a prevalence of B12 deficiencies in Mexican women of reproductive age 30.

Moreover, in the present study, both post-treatment IGF-1 and folic acid were correlated positively with their baseline values. Thus, baseline investigations for patients before isotretinoin therapy should include assessment of their status to minimize patients’ susceptibility to an evident and risky IGF-1 and folic acid deficiency.

However, we recommend reassessment of all the investigated parameters again after a follow-up period following stoppage of isotretinoin as reported changes might be transient and reversible.


Isotretinoin treatment, being a widely prescribed medication for acne, should be monitored closely before and following its use for plasma IGF-1, Hcy, folic acid, and vitamin B12. Younger patients should receive a more careful follow-up as they are at a higher risk of developing vitamin B12 deficiency; however, older patients should be monitored carefully for decrease in IGF-1 and its related side effects. Hyperhomocysteinemia and IGF-1 deficiency following isotretinoin therapy are correlated to each other and seems to be caused by the direct effect of isotretinoin on liver function, unrelated to vitamin B12 and folic acid deficiency, as no correlation was found between vitamin B12, folic acid, and Hcy levels. Vitamin B12 and folic acid therapy, together with isotretinoin, should be used only when deficient and its unnecessary use should be avoided.

Conflicts of interest

There are no conflicts of interest.


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folic acid; homocysteine; insulin-like growth factor-1; isotretinoin; vitamin B12

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