Can Hashimoto’s Disease Cause Kidney Problems?

Hashimoto’s disease can cause kidney problems through at least two distinct routes: the chronic shortage of thyroid hormones that defines the condition slows kidney filtration, and the autoimmune process itself may directly damage kidney tissue. A large cross-sectional study found that people with hypothyroidism had roughly double the odds of impaired kidney function compared to those with normal thyroid levels, even after accounting for other risk factors. The connection runs deeper than most patients realize, touching everything from subtle lab abnormalities to, in rare cases, acute kidney failure.

How Low Thyroid Hormones Slow the Kidneys

Your kidneys depend on adequate blood flow to filter waste from the blood. Thyroid hormones play a direct role in maintaining that flow by influencing both the heart’s output and the blood vessels within the kidneys themselves. When Hashimoto’s disease leaves you hypothyroid, the kidneys receive less blood, and their filtration rate drops accordingly.¹ This is not a small or theoretical effect. In a study of patients with untreated hypothyroidism, every single patient showed a decreased glomerular filtration rate, and more than half had elevated creatinine levels, a standard marker of impaired kidney function.²

A large population study involving tens of thousands of participants put numbers on the decline. Average kidney filtration rates dropped progressively from about 88 in people with normal thyroid function to about 83 in subclinical hypothyroidism and roughly 72 in overt hypothyroidism. After adjusting for age, diabetes, blood pressure, and other factors, people with hypothyroidism still had a 92 percent higher risk of having kidney function below the threshold that defines chronic kidney disease.³ The elderly tend to be hit harder, because they start with less kidney reserve and are more vulnerable to the hemodynamic slowdown that hypothyroidism causes.²

When the Immune System Targets the Kidneys Directly

The hemodynamic slowdown explains a lot, but it is not the whole story. Hashimoto’s is an autoimmune disease, and autoimmune diseases have a habit of not staying confined to one organ. Research has shown that the same antibodies your immune system produces against the thyroid, specifically anti-thyroid peroxidase (TPO) and anti-thyroglobulin (TG) antibodies, can deposit in kidney tissue. A clinicopathological study found that these thyroid-specific antibodies were significantly more prevalent in the glomeruli (the kidney’s filtering units) of patients who had autoimmune thyroid disease compared to those who did not.⁴

This antibody deposition can trigger various forms of glomerular disease. A biopsy study of patients with both Hashimoto’s and kidney involvement found a range of glomerular conditions, including focal segmental glomerulosclerosis, membranous glomerulonephritis, IgA nephropathy, minimal-change disease, and chronic glomerulonephritis.⁵ Membranous nephropathy, a condition where the glomerular membrane thickens and starts leaking protein, has been specifically linked to hypothyroidism in case reports, though it remains uncommon compared to the more typical causes like lupus or cancer.⁶

The practical implication is that if you have Hashimoto’s and develop unexplained proteinuria (protein in the urine) or worsening kidney function that does not fully track with your thyroid hormone levels, the autoimmune attack itself may be part of the problem, not just the hormone deficiency.

Proteinuria as an Early Warning

Protein leaking into the urine is one of the earliest signs of kidney stress, and it shows up more frequently in people with hypothyroidism. In the same large population study mentioned earlier, proteinuria rates climbed from about 1.3 percent in people with normal thyroid function to roughly 2.2 percent in subclinical hypothyroidism and about 3 percent in overt hypothyroidism.³ A separate analysis found positive correlations between hypothyroidism and urinary protein in patients without diabetes, though interestingly the association weakened in those who did have diabetes, possibly because diabetic kidney disease is already so dominant in that group.⁷

This matters because proteinuria is not just a passive marker. Persistent protein in the urine accelerates further kidney damage over time, creating a cycle where thyroid-driven kidney stress leads to proteinuria, which in turn worsens the kidney’s trajectory. If you have Hashimoto’s and your doctor checks only your thyroid levels at routine visits, mild proteinuria could go unnoticed for years.

Even Subclinical Hypothyroidism Counts

Many people with Hashimoto’s spend months or years in a state of subclinical hypothyroidism, where the thyroid is struggling but still producing enough hormone to keep blood levels in a borderline-normal range. It would be comforting if the kidneys were spared during this phase, but the evidence suggests otherwise. The population data above showed that subclinical hypothyroidism doubled the unadjusted odds of impaired kidney function compared to normal thyroid levels.³ A review of the relationship between thyroid autoimmunity and chronic kidney disease cited a study of over 1,400 Japanese women showing that the prevalence of chronic kidney disease was significantly higher in women with Hashimoto’s than in those without, and the disease tended to be more severe.⁸

This is relevant to the ongoing debate about whether subclinical hypothyroidism should be treated with medication. From a kidney perspective, the data leans toward earlier intervention rather than a watch-and-wait approach, though the decision involves weighing other factors too.

Acute Kidney Injury From Hashimoto’s

Most kidney effects from Hashimoto’s develop gradually, but in rare cases, the disease can trigger acute kidney injury. The most dramatic path involves rhabdomyolysis, a condition in which muscle tissue breaks down rapidly and floods the kidneys with a protein called myoglobin. Hypothyroidism causes muscles to become sluggish and prone to breakdown, and this has been documented as a direct complication. One case report described a 42-year-old man with no prior health problems who developed severe rhabdomyolysis and acute kidney injury from hypothyroidism caused by Hashimoto’s, without any other precipitating factors like extreme exercise or trauma.⁹

Another documented scenario involves reversible acute kidney injury from the hemodynamic effects alone. In one case of a patient with Hashimoto’s-related primary hypothyroidism, kidney function returned to normal after 11 months of thyroid hormone replacement, with very high thyroid antibody levels confirming the autoimmune origin.¹⁰ These cases are uncommon, but they highlight that unexplained kidney failure in someone with untreated or undertreated Hashimoto’s should prompt a close look at thyroid function.

Electrolyte Disruptions

Hypothyroidism also affects the kidneys’ ability to handle water and sodium, sometimes causing hyponatremia, meaning dangerously low sodium levels in the blood. The main mechanism involves changes in antidiuretic hormone levels. When hypothyroidism reduces cardiac output, the body responds by holding onto more water, which dilutes the blood’s sodium concentration.¹¹ At least one careful case study, however, concluded that the effect is a direct renal mechanism rather than purely a hormone-driven water-retention problem, suggesting the kidneys themselves lose their ability to excrete free water efficiently in hypothyroidism.¹²

Mild hyponatremia can cause confusion, fatigue, and nausea, symptoms that easily get blamed on the thyroid condition itself and go uninvestigated. Severe cases can lead to seizures or altered consciousness. If you have Hashimoto’s and experience unexplained cognitive sluggishness that seems worse than your thyroid levels would predict, checking your sodium is worth the blood draw.

Does Treating Hashimoto’s Help the Kidneys Recover?

The good news is that much of the kidney damage from Hashimoto’s is reversible, especially if it is caught before it becomes chronic. The hemodynamic slowdown responds to thyroid hormone replacement. In a study of patients with chronic kidney disease and subclinical hypothyroidism, those treated with levothyroxine saw their rate of kidney decline dramatically slow, from about 4.3 units per year to roughly 1 unit per year, compared to untreated patients whose kidneys kept deteriorating at the faster rate.¹³ Another study found that levothyroxine actually increased kidney filtration rates over time, with the strongest benefit in patients who had stage 3 chronic kidney disease.¹⁴

There are limits, though. Autoimmune glomerular damage that has already scarred the kidney tissue is unlikely to reverse with thyroid treatment alone. And in children with primary hypothyroidism, kidney function improved substantially after starting thyroxine therapy but did not fully normalize even after one to five years, suggesting some residual effect persists.¹⁵ The takeaway is that earlier treatment preserves more kidney function, and waiting until kidney damage is advanced means accepting some loss that cannot be reclaimed.

Children With Hashimoto’s and Kidney Function

The kidney effects of Hashimoto’s are not limited to adults. A study evaluating kidney function in children with Hashimoto’s found that they could present with reduced filtration rates and proteinuria, and that both improved with thyroid hormone replacement therapy.¹⁶ Separately, research tracking children with hypothyroidism over time found that about 58 percent had a filtration rate more than two standard deviations below normal before treatment. One to six months after starting thyroxine, that dropped to about 31 percent. But even at the last follow-up, one to five years later, their average filtration rate remained measurably lower than that of healthy children.¹⁵

For parents of children diagnosed with Hashimoto’s, this is a reason to ensure kidney function gets checked at diagnosis and periodically thereafter, especially because children are unlikely to report vague symptoms like mild fatigue or changes in urination frequency.

A Lab Test Wrinkle Worth Knowing About

If you have Hashimoto’s and your doctor uses cystatin C to estimate kidney function, be aware of an important quirk. Cystatin C is a protein produced by nearly all cells in the body, and its blood level is commonly used as a marker of how well the kidneys are filtering. But thyroid status directly affects cystatin C levels independent of kidney function. In hypothyroidism, cystatin C tends to be lower, and in hyperthyroidism, it runs higher, regardless of actual kidney filtration.¹⁷

A pilot study of hypothyroid patients on levothyroxine found that those with suboptimal thyroid hormone levels had significantly higher cystatin C levels than those with well-controlled levels, even though their actual measured kidney function was the same between groups.¹⁸ In practice, this means cystatin C can overestimate kidney function in untreated hypothyroidism and potentially underestimate it during treatment if thyroid levels are running high. Standard creatinine-based estimates are more reliable in this population, or at minimum, cystatin C results should be interpreted alongside thyroid function tests.

The Traffic Runs Both Ways

The relationship between thyroid and kidney is genuinely bidirectional. Not only can Hashimoto’s harm the kidneys, but kidney disease can disrupt thyroid function too. Severe nephrotic syndrome, a kidney condition involving massive protein loss in the urine, causes the kidneys to flush out thyroid hormones and thyroid-binding proteins along with everything else. One study found that patients with nephrotic syndrome had dramatically higher rates of both euthyroid sick syndrome and frank hypothyroidism compared to controls, with about a quarter requiring levothyroxine supplementation.¹⁹

This creates a potential vicious cycle: Hashimoto’s worsens kidney function, and worsening kidney function further depletes thyroid hormones, which in turn accelerates kidney decline. Breaking this cycle usually requires treating the thyroid aggressively while addressing the kidney disease in parallel. Researchers have recommended routine thyroid screening for all patients with chronic kidney disease for exactly this reason.²⁰

Autoimmune Overlap and Kidney Risk

People with one autoimmune disease are at higher risk of developing others, and some of those overlapping conditions carry serious kidney consequences. The best-studied example is the coexistence of Hashimoto’s with systemic lupus erythematosus, a condition that frequently attacks the kidneys. Case reports have documented patients presenting with Hashimoto’s, lupus, and IgA nephropathy simultaneously.²¹ The coexistence has been reported across different populations and geographic settings.²²

This matters practically because if you have Hashimoto’s and develop kidney symptoms that seem disproportionate to your thyroid status, the culprit may not be the Hashimoto’s alone. An overlapping autoimmune condition affecting the kidneys could be at work, and the diagnostic approach, particularly whether a kidney biopsy is warranted, changes depending on what is suspected.

Hashimoto’s, Pregnancy, and Kidney Stress

Pregnancy places enormous demands on the kidneys, which must filter a significantly larger blood volume for months. Hashimoto’s adds to that burden in a specific way. A nationwide analysis of hospital records from 2016 to 2020 found that autoimmune thyroiditis was independently associated with a 22 percent increase in the risk of preeclampsia, a condition defined partly by kidney dysfunction (proteinuria and high blood pressure).²³ The same study found elevated risks for gestational diabetes and fetal growth restriction.

For women with Hashimoto’s who are pregnant or planning to become pregnant, this means close monitoring of blood pressure and kidney markers is more than routine caution. The thyroid autoimmunity itself appears to contribute to preeclampsia risk above and beyond whatever effect hypothyroidism alone might have, possibly through the same immune-mediated vascular inflammation that damages kidney tissue in non-pregnant patients.

Animal Research and the Renin-Angiotensin Connection

Much of our understanding of the fine-grained mechanisms involved comes from animal studies. Research in hypothyroid rats showed that the changes in kidney blood flow and filtration dynamics mirrored what happens when the renin-angiotensin system, a hormone system that regulates blood pressure and fluid balance, is overactivated. Interestingly, the tubular function of the kidney dropped off faster than the overall blood flow changes, falling to its lowest within one week while the vascular effects took three weeks to fully develop.²⁴ This fits with the clinical observation that thyroid hormones affect both the pre-renal circulation (blood getting to the kidney) and the intrinsic kidney tissue itself.¹

The renin-angiotensin angle is clinically meaningful because many patients with early kidney disease are already on medications that block this system, such as ACE inhibitors or ARBs, for blood pressure or proteinuria management. In someone with Hashimoto’s, addressing the thyroid deficiency may partially reduce the need for aggressive renin-angiotensin blockade, or at least change how the medications interact with the underlying physiology. This is a conversation worth having with your doctor rather than guessing at dose adjustments on your own.

1
PubMed Central. Interactions between thyroid disorders and kidney disease
2
PubMed. Changes in renal function in primary hypothyroidism
3
Scientific Reports. Subclinical and overt hypothyroidism is associated with reduced glomerular filtration rate and proteinuria: a large cross-sectional population study
4
PubMed Central. Relationship between autoimmune thyroid disease and nephropathy: a clinicopathological study
5
PubMed. Coexistent findings of renal glomerular disease with Hashimoto’s thyroiditis
6
PubMed Central. Membranous nephropathy associated with profound hypothyroidism
7
Scientific Reports. The association between hypothyroidism and proteinuria in patients with chronic kidney disease: a cross-sectional study
8
PubMed Central. Interrelationship between thyroid hormones and reduced renal function, a review article
9
PubMed Central. Severe hypothyroidism‐induced rhabdomyolysis: A case report
10
ScienceDirect (Kidney International Reports). 152 HYPOTHYROID INDUCED REVERSIBLE ACUTE KIDNEY INJURY – AN OFTEN FORGOTTEN CAUSE
11
European Journal of Endocrinology. Hypothyroidism-associated hyponatremia: mechanisms, implications and treatment
12
The Netherlands Journal of Medicine. Hyponatremia due to hypothyroidism: a pure renal mechanism
13
PubMed Central. Thyroid hormone replacement therapy attenuates the decline of renal function in chronic kidney disease patients with subclinical hypothyroidism
14
PubMed Central. FAVORABLE EFFECT OF LEVOTHYROXINE ON NUTRITIONAL STATUS OF PATIENTS WITH STAGE 3-4 CHRONIC KIDNEY DISEASE
15
PubMed. Long-term effects of primary hypothyroidism on renal function in children
16
Annals of Medical Research. Evaluation of kidney function in children with Hashimoto’s Thyroiditis
17
PubMed. Impact of thyroid dysfunction on serum cystatin C
18
PubMed Central. Cystatin C, a Controversial Biomarker in Hypothyroid Patients under Levothyroxine Therapy: THYRenal, a Pilot Cohort Observational Study
19
PubMed Central. The impact of severe nephrotic syndrome on thyroid function, nutrition and coagulation
20
European Journal of Cardiovascular Medicine. Thyroid Profile in Patients with Chronic Kidney Disease -A Cross sectional study at a tertiary care centre
21
PubMed. Coexistence of systemic lupus erythematosus, Hashimoto’s thyroiditis and IgA nephropathy in the same patient
22
PubMed Central. Concurrent Systemic Lupus Erythematosus and Hashimoto’s Thyroiditis: Clinical Patterns From Two Cases in Southwestern Nigeria
23
PubMed Central. Effects of Autoimmune Thyroiditis on Pregnancy Outcomes: Analysis of the Nationwide Inpatient Sample, 2016-2020
24
PubMed. Glomerular dynamics in the hypothyroid rat and the role of the renin-angiotensin system