Study of Association of Sensory Neural Hearing Loss with Iron Deficiency Anaemia

Abstract

Hearing loss is an ignored community health problem. Along with various mental and motor developmental impairments, iron deficiency anemia (IDA) may cause hearing abnormalities. Study aimed to correlate the Sensorineural hearing loss with iron deficiency anemia in adults. This case control study conducted. Total of 200 participants fulfilling the inclusion criteria were included in present study and grouped into group 1 as cases and group 2 as controls. The participants included in present study after obtaining the consent and evaluated for the iron profile, PTA, OAE for sensory neural hearing loss. They were followed up for 3 months and 6 months. The mean age of case was 41.9 ± 10.77 and there was female preponderance in present study with 120 female and 80 males. Among 100 participants with iron deficiency anemia, twenty among them had the SNHL. The hearing impairment improved with the treatment of the IDA in patients in follow-up. There is a significant association between the SNHL and the Iron deficiency anemia in the patient. The treatment of IDA improves the hearing loss among the adults.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-021-02619-4.

Introduction

Hearing loss is an ignored community health problem that affects an estimated 360 to 554 million adults and children in the world. The hearing threshold accepted overlook milder hearing loss [1, 2]. The hearing loss appears at a young age increases with multiple folds with increasing age and it affects all parts of a healthy being. The prevalence of hearing loss is high in low-income backgrounds, especially in South Asia and sub-Saharan Africa.

Hearing loss has affects health, social, and economic concerns. Adults affected face higher risks of unemployment and low per capita income, cognitive decline, and dementia. Another risk is social isolation which comes with hearing loss [2].

Iron deficiency anemia (IDA) is a type of anemia that typically includes reduced hemoglobin, serum iron, serum Ferritin and/or decreased soluble transferrin receptor in patients. IDA can be typically be handled effectively by oral iron. The precise mechanism by which IDA leads to hearing loss is largely unclear. It's still uncertain if IDA therapy is enhancing hearing quality. Nevertheless, it was commonly speculated to be linked to the cochlea’s vulnerability to IDA’s vascular and neurological impacts. Cochlear only comes from the labyrinthine artery. Lack of collateral circulation could make it more ischemically vulnerable [3, 4].

Along with various mental and motor developmental impairments, iron deficiency anemia (IDA) may cause hearing abnormalities. IDA is a commonly occurring nutritional clinical disorder. A causal relationship between the severity of IDA and extent of hearing abnormalities has been suggested [2].SNHL may have IDA-potentially aggravated vascular etiology, as defined in an iron deficiency rat model and sudden SNHL. This research identified cochlear defects like strial atrophy [5] and reduced spiral ganglion cells with effects on the inner and outer hair cell stereocilia [5, 6]. The mechanism of iron in the vasculature and nervous system makes its association with other specific forms of adult hearing loss possible beyond sudden SNHL.

To our knowledge, the effect of IDA on hearing loss has been less investigated previously in India. Because IDA is a common and easily correctable disorder, further understanding of the association between IDA and hearing loss in adults may help for timely identification and proper treatment.

The main aim of the study is Study aimed to correlate the Sensorineural hearing loss with iron deficiency anemia in adults.

The main Objectives is to (i) To evaluate the association between sensory neural hearing loss and iron deficiency anaemia in adults aged 18–60 years. (ii) To assess the sensory neural hearing loss after treatment of iron deficiency anaemia.

Materials and Method

This is a case control study for a total period of One and half years with Convenience Sampling with 100 people in each group i.e., cases and control, cases included people who gave consent for the study with iron deficiency anaemia were evaluated with pure tone audiometry (PTA) and otoacoustic emission (OAE) for sensory neural hearing loss at the first visit, after which they were started on standard treatment for iron deficiency anaemia and was followed up after 3 months and 6 months with the Hb, S.Ferritin, S.Transferrin, PTA, OAE. The Ethical clearance was taken from the ethical committee of the university.

The Inclusion Criteria being Adults with iron deficiency anemia in the age group of 18 to 60 years and Exclusion Criteria being (1) Those with conductive hearing loss in the age group (2) Patients with diabetes and hypertension (3) Patients with any co-morbidities associated with IDA. A hearing threshold of more than 20 dB in PTA was defined as any hearing loss.

Controls were selected randomly healthy subjects in the age group 18–60 yrs.

The grading of anaemia was based on the levels of Hb,TIBC and S.Ferritin.

Grading of Iron deficiency anaemia based on hemoglobin percentage (g/l) [7].

Population	Non Anaemia*	Mild	Moderate	Severe
Non-pregnant women (15 years of age and above	120 or higher	110–119	80–109	lower than 80
Pregnant women	110 or higher	100–109	70–99	lower than 70
Men (15 years of age and above)	130 or higher	110–129	80–109	lower than 80

Normal range of Total iron binding capacity (TIBC) and Ferritin levels (42).

Total iron-binding capacity	250–450 μg/dL (45–81 μmol/L)
Ferritin	30–300 ng/mL (30–300 μg/L)

Results

A Total of 200 participants included in present study. They were distributed into two groups as.Group 1: Case—participants with anemia, Group 2: Control—participants without anemia. The mean age of the participants in both the group were 41.99 ± 10.77 yrs in cases and in controls it was 43.99 ± 9.77 yrs. The study subjects included in present study showed a preponderance of the female population, and the anemia among the females was more common than in the males.

The patients presented with the presence of tinnitus (12%), aural fullness (12%), history of vertigo (15%), history of dysphagia (12%), neuralgia (1%). Generalised weakness being the most common presenting symptom (Fig. 1).

Fig. 1.

Symptoms presenting at first visit

There was a significant difference in the mean values of the PTA of both right and left ear (Fig. 2) among the controls and the cases. the overall PTA of right ear and of left ear was significantly higher in the cases (n = 100) than in the controls (n = 100). On evaluation with the Distortion Product Otoacoustic Emission (DPOAE) in both the ears, the absence of DPOAE was significantly higher among the patients with anemia (group 1) compared to the group 2 participants. all the 100 controls passed the DPOAE evaluation in both the ears (right & left) (Table 1).

Fig. 2.

Overall PTA between two groups before treatment

Table 1.

Showing the comparison of DPOAE among cases and controls

		Group
		Case	Control	Chi-square
		Count	Count	(sig)
Right DPOAE	Absent	19	0	20.994 (0.001)
	Pass	81	100
Left DPOAE	Absent	14	0	15.054 (0.001)
	Pass	86	100

The Sensorineural hearing loss was found in 20 patients and all the twenty were in the group 1 with anemia. 10 patients had SNHL left more than the right and 10 patients were with SNHL right more than left. On evaluation of the anemia profile, there is a significant low serum iron and the ferritin among the participants with the anemia compared to the controls. There was also improvement in the serum iron, ferritin and the TIBC among the 20 patients with SNHL at the 3rd month and the 6th month. With the improvement in the nutritional status and the serum ferritin and iron levels, there was improvement in the PTA result of both right and left year at the 3rd month and 6th month. Similarly, the overall PTA of right and left ear improved significantly at the 6th month of treatment follow-up. 20% of patients with the iron deficiency anemia found to have SNHL (Table 2).

Table 2.

Showing the improvement in the hemoglobin, serum TIBC, Ferritin and iron among the SNHL patients at follow-up

	Group
	1st Month (a)		3rd Month Followup (b)		6th Month Followup (c)
	Mean	SD	Mean	SD	Mean	SD
Hemoglobin in Gm%	6.18	1.80	8.04 *a	1.17	9.49 *a,b	.97
TIBC in microg/dL	413.00 *c	96.41	413.00 *c	96.41	303.05	73.81
Serum Ferritin in ng/mL	20.28	29.34	20.28	29.34	131.90 *a,b	81.45
Serum Iron in microg/dL	26.56	9.08	26.56	9.08	58.15 *a,b	24.78

Tinnitus being one of the common presenting symptom among cases was evaluvated with THA score (Fig. 3). The THA score of the 20 patients improved significantly with the improvement in the anemia and the iron levels. There was improvement in the DPOAE result with improvement in the anemia, serum iron and ferritin level (Tables 3, 4).

Fig. 3.

THI score and improvement with treatment

Table 3.

Showing the improvement in the PTA during the follow-up of SNHL patients

	Group
	1st Month		3rd Month Followup		6th Month Followup
	Mean	SD	Mean	SD	Mean	SD
Right PTA 500 Hz	20.60	2.26	20.00	1.84	19.70	1.49
R_PTA1000	34.60	5.20	32.90	4.83	30.60	4.95
R_PTA2000	46.60	6.01	44.40	5.57	41.70	4.69
R_PTA4000	56.00	4.54	53.40	4.45	50.70	4.46
R_PTA8000	69.10	8.67	68.20	9.20	67.40	9.38
R_OVERALL	38.73	2.80	37.01	2.71	35.10	2.64
L_PTA500	20.50	2.14	19.40	1.73	19.40	1.73
L_PTA1000	34.30	6.17	32.10	6.00	30.10	5.75
L_PTA2000	45.60	9.48	42.90	9.48	40.40	8.79
L_PTA4000	55.45	9.73	53.85	8.85	51.10	7.99
L_PTA8000	66.35	14.55	65.75	14.29	64.75	14.10
L_OVERALL	43.36	9.26	41.29	8.66	39.18	7.83

Table 4.

Showing the improvement in the DPOAE among the SNHL patients at follow-up

		Group
		1st Month	3rd Month Followup	6th Month Followup	Chi-square
		Count	Count	Count	(sig)
Right DPOAE	Absent	19	17	11	11.69 (0.05)
	Pass	1	3	9
Left DPOAE	Absent	14	14	13	9.24 (0.049)
	Pass	6	6	7

Discussion

Synopsis of Key Finding

The mean age of case was 41.9 ± 10.77 and control was 43.9 ± 9.7 (p > 0.05) with female preponderance,generalized weakness being the most common complaint to present. There was Significant low hemoglobin (6.55 ± 1.83)higher TIBC (446.14 ± 98.68) low serum ferritin (13.69 ± 21.33) low serum iron (25.05 ± 9.02) in cases compared to controls. There is highly significant difference in the overall PTA scores, DPOAE in cases compared to control (p < 0.001).

Discussion

Hearing loss increases with each decade of life, affecting 40–66% of adults older than 65 years and 80% of those older than 85 years [8]. Iron deficiency anemia (IDA) is a subset of anemia in which patients usually exhibit low hemoglobin, serum ferritin, serum iron, and/or increased soluble transferrin receptor. It can usually be easily treated with oral iron supplementation. This analysis shows a potential association between IDA and SNHL. A total of 200 participants included in present study, the demographic details are as follows.

The mean age of the participants in our study in both the group were 41.99 ± 10.77 yrs in cases and in controls it was 43.99 ± 9.77 yrs which was similar to a population based study in Taiwan done by Chung SD et al. [9] found that there is substantial link between SNHL and prior IDA was most pronounced among those 44 years or younger.In many studies the age of presentation was between the 35-55yrs of age and lower than 60 yrs of age with nutritional deficiency or anemia [3, 9].

The study subjects included in present study showed a preponderance of the female population, and the anemia among the females was more common than in the males. Various studies have recorded the prevalence of anemia including the iron deficiency anemia being more common among the women than the males like that of a population based study done by Levi M, Simonetti M, Presence of anemia is more common among the women and children’s compared to adult men. In contrast to our study, study by Nosrati-Zarenoe R, have documented a equal incidence of the SNHL in both men and women.

Among the 200 patients included, 100 were grouped into the anemia category. Among the cases, 20 were with the hearing loss. The patients presented with the presence of tinnitus (12%), aural fullness (12%), history of vertigo (15%), history of dysphagia (12%), neuralgia (1%).

There was a significant difference in the mean values of the PTA of both right and left ear among the controls and the cases. the overall PTA of right ear and of left ear was significantly higher in the cases (n = 100) than in the controls (n = 100). On evaluation with the Distortion Product Otoacoustic Emission (DPOAE) in both the ears, the absence of DPOAE was significantly higher among the patients with anemia (group 1) compared to the group 2 participants. all the 100 controls passed the DPOAE evaluation in both the ears (right & left).

The Sensorineural hearing loss was found in 20 patients and all the two were in the group 1 with anemia. 10 patients had SNHL left more than the right and 10 patients were with SNHL right more than left.

On evaluation of the anemia profile, there is a significant low serum iron and the ferritin among the participants with the anemia compared to the controls. On follow-up, the weight of all the 20 participants improved significantly.

There was also improvement in the serum iron, ferritin and the TIBC among the 20 patients with SNHL at the 3rd month and the 6th month. With the improvement in the nutritional status and the serum ferritin and iron levels, there was improvement in the PTA result of both right and left year at the 3rd month and 6th month. Similarly, the overall PTA of right and left ear improved significantly at the 6th month of treatment follow-up. 20% of patients with the iron deficiency anemia found to have SNHL.

The higher frequencies were affected (4000, 8000) than the lower frequencies (500, 1000, 2000). The improvement in the hearing g for higher frequencies was significant as compared to lower frequencies.

The THA score of the 20 patients improved significantly with the improvement in the anemia and the iron levels. There was improvement in the DPOAE result with improvement in the anemia, serum iron and ferritin level. Similar findings were documented by various studies, there is a significant improvement in hearing loss with improvement in the iron deficiency anemia [2, 6, 8, 10].

The results indicate that the Iron deficiency anaemia should be considered in SNHL patients and for more active treatment of IDA patients, specially patients less than 60 years. Some of the main hypotheses regarding SNHL's pathogenesis is vascular cochlea dysfunction caused by embolus, thrombus, decreased blood flow, or vasospasms. Based on that interpretation, many diseases consider SNHL to be a comorbidity. The correlation with SNHL between increased cardiovascular and cerebrovascular risk is well documented [9].

IDA is common variant of anaemia and accounts for more than 50% of all the cases. The disease is due to inadequate food consumption and iron absorption or iron deficiency due to bleeding of the intestinal, uterine, or urinary tracts or otherwise. It is easy to understand that a drop in bloodstream Hb levels would possibly result in inadequate oxygen supply to the tissue. Many findings have implicitly indicate ischemic stroke as one of the risk factors [11]. Addition, several studies have well reported adverse cerebrovascular and cardiovascular effects associated with reduced concentrations of hemoglobins [9].

While it seems thoughtful that the hemodynamic disturbance in Iron deficiency anaemia may lead to vascular compromise theory of SNHL, results based on a temporal bone histopathology study indicate that viral origin than a vascular origin for SNHL. Concepts of membrane cracks, perilymphatic fistulae and vascular occlusions are being thought for causes of idiopathic SNHL, and new mechanisms involving the pathological activation of cellular stress pathways are being suggested.

Comparision with Other Studies

In a study conducted by Sun AH et al. (1991) to study iron deficiency and hearing loss in growing rats showed Strial atrophy and reduction of spiral ganglion cells were the principal cochlear histopathological changes induced by iron deficiency. It is concluded that the observed abnormalities can only be due to a cochlear tissue iron deficiency.

In study by Sun AH et al.224 patients with SNHL, the authors concluded that red cell basic ferritin concentration were considerably lower than those in normal hearing controls [12].

In 62 normal hearing healthy subjects and 224 patients with specific sensorineural hearing loss compared to serum ferritin, haemoglobin, serum iron and circadian serum iron levels. The findings showed that the concentrations of RCBF were substantially lower in most cases of sensorineural hearing loss than those in normal hearing status.

In a study done by Schieffer KM et.al. (2017) Both SNHL (present in 26 of 2274 individuals [1.1%] with IDA; P = 0.005) and combined hearing loss (present in 77 [3.4%]; P < 0.001) were significantly associated with IDA [8].

In a meta-analysis study conducted by Mohammed SH et.al.(2019) to assess the association of anemia with Sensorineural hearing loss. IDA may be a factor leading to hearing loss an important consideration may be hearing loss screening in anemic individuals, or vice-versa [7].

Limitations and Recommendations

The recommendations of the study is that as IDA is one of the most common type of anaemia,and hearing loss in IDA could be prevented if diagnosed early hence a PTA for all IDA patients would be recommended. The limitations of the study was its sample size and financial limitations. It is recommended to conducted research on this topic addressing the above two limitation, to draw more statistically sound data.

Conclusion

There is association between the iron deficiency anemia in adults with the Sensorineural hearing loss. The early intervention and treatment of the underlying cause of iron deficiency can help to improve the hearing and reduce the suffering with SNHL. The patient attending the OPD for hearing loss in the young adults should be screen for the anemia particularly the iron deficiency anemia, which can be treated by early intervention with the supplementation of oral iron.

Supplementary Information

Below is the link to the electronic supplementary material.

Declarations

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical Approval

This article does not contain any studies with animals performed by any of the authors. Informed consent was obtained from all individual participants in the study.