Thyroid disorders can sometimes lead to urinary retention, which is the inability to completely empty the bladder. Urinary retention is an uncommon but possible complication of both hyperthyroidism and hypothyroidism. In this article, we will explore the connection between thyroid dysfunction and urinary retention and discuss the mechanisms by which thyroid problems may contribute to voiding difficulties. We will also outline the diagnostic approach for patients with concurrent thyroid and urinary issues and review the treatment options.
Overview of the thyroid gland
The thyroid gland is a small, butterfly-shaped organ located at the base of the neck. It produces thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3), which regulate metabolism, growth, development, and many other essential body functions.
The thyroid is regulated by thyroid-stimulating hormone (TSH), which is made by the pituitary gland. When TSH binds to receptors on thyroid cells, it stimulates the production and release of T4 and T3. The thyroid hormones then provide negative feedback to the pituitary, decreasing further TSH production when adequate hormone levels are reached.
Hyperthyroidism
Hyperthyroidism refers to the overproduction of thyroid hormones. Some common causes include 1:
- Graves’ disease – autoimmune condition
- Toxic nodular goiter – nodules produce excess hormones
- Thyroiditis – inflammation of the thyroid
- Excess iodine intake
- Taking too much synthetic thyroid hormone
In hyperthyroidism, high levels of circulating thyroid hormones speed up metabolism and can affect many organ systems.
Hypothyroidism
In contrast, hypothyroidism is characterized by an underactive thyroid with inadequate hormone production. Causes include 2:
- Hashimoto’s thyroiditis – autoimmune destruction of the thyroid
- Surgical removal of part/all of the thyroid
- Radiation treatment to the thyroid or neck
- Congenital hypothyroidism – thyroid dysfunction from birth
- Pituitary disorder leading to low TSH
- Certain medications
With reduced thyroid hormones, the body’s metabolism slows down considerably.
Mechanisms linking thyroid dysfunction and urinary retention
Thyroid hormones affect many tissues, including the kidneys and urinary system. Both excess and insufficient hormone levels can potentially alter normal urinary tract function.
Hyperthyroidism
Several mechanisms may explain urinary retention in hyperthyroidism3:
- Increased kidney blood flow and glomerular filtration rate, resulting in increased urine production and frequency, promoting bladder distension
- Smooth muscle relaxation of the urinary sphincter and detrusor muscle of the bladder wall, impairing voiding
- Autonomic nervous system imbalance with heightened sympathetic tone, disrupting coordinated bladder contraction
- Weakness of pelvic floor muscles
The increased diuresis and impaired voiding coordination promote urinary retention and incomplete bladder emptying. Residual urine then further stretches the weakened detrusor muscle, worsening the problem.
Hypothyroidism
Proposed mechanisms by which hypothyroidism may cause urinary retention include4:
- Slowing of overall metabolism and kidney function, decreasing urine output
- Estrogen deficiency which may promote urinary tract dysfunction
- Fluid retention caused by hormone changes
- Constipation straining the pelvic floor
- Peripheral neuropathy affecting the bladder
- Impaired bladder contractility
The end result may be incomplete bladder emptying and large post-void residuals. Of note, hypothyroid patients tend to report urinary symptoms less frequently than those with hyperthyroidism5.
Diagnosis
Patients with concurrent thyroid dysfunction and urinary retention require a systematic diagnostic approach:
History and physical examination
Key points in the history include6:
– Symptoms of thyroid disorder (e.g. heat/cold intolerance, weight changes, fatigue)
– Lower urinary tract symptoms – weak stream, hesitancy, incomplete emptying, frequency
– Medication list – drugs affecting thyroid or urination
– Relevant past medical and surgical history – prostate issues, neurologic disorders
On exam, findings may include7:
– Altered vital signs consistent with hyper/hypothyroidism
– Cardiovascular, skin, and neuromuscular changes
– Abdominal/pelvic exam – bladder distension, prostate enlargement
– Signs of systematic fluid retention
– Neurological testing – assess peripheral nerves, sphincter tone
Laboratory testing
– Thyroid function tests – TSH, T4, T3, thyroid antibodies
– Complete blood count, metabolic panel
– Urine studies – urinalysis, culture
– Serum BUN/creatinine if acute kidney injury suspected
Imaging
– Thyroid ultrasound – assess morphology, nodules, thyroiditis
– Bladder/urinary tract ultrasound
– Post-void residual (PVR) urine volume
– Exclude urinary obstruction
Urodynamic studies
– Cystoscopy – directly visualize bladder wall and outlet
– Uroflowmetry – assess flow rate
– Pressure-flow studies – evaluate detrusor contractility and urinary sphincter function
– Electromyography – analyze pelvic floor muscle activity
Bladder diaries and voiding logs
– Track frequency, volumes, incontinence, retention episodes
– Correlate with food/fluid intake, medications
Treatment approach
Treatment focuses on addressing both the thyroid dysfunction and urinary retention:
Correcting the thyroid disorder
– Hyperthyroidism – anti-thyroid medications, radioactive iodine, surgery
– Hypothyroidism – levothyroxine replacement
Achieving a euthyroid state may improve urinary retention in many patients.
Addressing obstructive causes
– Alpha-blockers, 5-alpha reductase inhibitors for prostatic obstruction
– Consider surgery if refractory to medical therapy
Behavioral modifications
– Timed and double voiding
– Fluid management
– Bowel regimen for constipation
– Smoking cessation
Medications to improve bladder emptying
– Cholinergic agonists
– Beta-3 adrenergic agonists
– Mirabegron
Intermittent self-catheterization
– Regularly empty bladder if unable to void adequately
Surgeries
– Prostate surgery – TURP, laser
– Botulinum toxin bladder injections
– Sacral neuromodulation
– Bladder augmentation
Treatment is individualized based on the patient’s specific defects in bladder function and comorbidities. Combination therapy is frequently needed to fully manage the urinary retention.
Role of the Endocrinologist
Given the complex interplay between thyroid disorders and urinary dysfunction, a multidisciplinary approach is ideal.
– The endocrinologist diagnoses and treats the underlying thyroid condition.
– Close communication with urologists and primary care is needed to coordinate care.
– Endocrinologists can advise on potential impact of thyroid treatment on lower urinary tract symptoms.
– Important to recognize medication interactions – e.g. hypertension drugs worsening voiding.
– May need to modify thyroid replacement dosing in context of renal insufficiency from obstructive uropathy.
– Help determine whether bladder issues are due to residual thyroid imbalance vs separate pathophysiological process.
The impact of achieving a euthyroid state
Studies examining the effects of thyroid disease treatment on urinary retention have shown mixed results:
| Study | Number of Patients | Thyroid Condition | Treatment Effect on Urinary Retention |
|---|---|---|---|
| Tepeler et al, 20078 | 24 men | Hyperthyroidism | Significant improvement in IPSS, Qmax, and PVR with anti-thyroid treatment |
| Kahlen et al, 19969 | 47 men, 8 women | Hyperthyroidism (n=41), Hypothyroidism (n=14) | No significant difference in voiding after reaching euthyroid state |
| Erbagci et al, 200210 | 32 women | Hypothyroidism | No change in urodynamic parameters with levothyroxine therapy |
While some studies showed improvement in voiding parameters with thyroid disease treatment, others found no significant difference. There are several potential reasons for these contradictory findings:
– Differences in underlying mechanisms and severity of urinary retention
– Concurrent bladder outlet obstruction or neurogenic dysfunction
– Small sample sizes
– Residual low-grade thyroid hormone imbalance
– Delay between restoring euthyroidism and urologic re-evaluation
– Other comorbid factors contributing to voiding dysfunction
Overall, the results emphasize the importance of a patient-centered approach when managing concurrent thyroid and urinary syndromes.
Special considerations in treating the elderly
The elderly often have voiding issues and are at higher risk for thyroid problems. Important considerations in this population include:
– More frequent monitoring of thyroid levels due to increased labile TSH11
– Potential need for reduced levothyroxine dose due to decreased renal clearance
– Higher likelihood of unrecognized thyroid dysfunction
– Increased prevalence of comorbidities such as heart disease, diabetes
– Greater impact of polypharmacy leading to medication interactions
– Consider role of estrogen deficiency in postmenopausal women
– High probability of prostatic enlargement contributing to voiding dysfunction in older men
– More careful titration of medications for urinary retention to avoid exacerbating hypotension
– Increased fall risk with medications causing frequenty or urgency
– Consider OT consultation regarding functional impairments interfering with toileting
A collaborative approach between endocrinology, geriatrics, urology, and primary care is very important when managing older patients.
Conclusion
In summary, the complex interactions between thyroid hormone activity and lower urinary tract function can occasionally result in urinary retention in the setting of hyperthyroidism or hypothyroidism. Key points include:
– Multiple mechanisms including smooth muscle dysfunction, autonomic imbalance, and renal effects may be involved.
– Systematic evaluation is required in patients with concurrent thyroid and urinary complaints.
– Treatment centers on restoring a euthyroid state and directly managing the urinary retention.
– The impact of achieving normal thyroid hormone levels on bladder emptying is still unclear.
– Individualized, multidisciplinary care is essential for optimal patient outcomes.
– Additional considerations are needed when treating older patients with thyroid and voiding disorders.
While thyroid disorders are certainly not the most common cause of urinary retention, the possibility of this association warrants awareness and consideration during evaluation. Patients may benefit from screening for thyroid dysfunction if urinary retention arises and standard treatments prove ineffective. Further research is still needed to better elucidate the intricate relationship between hypothyroidism, hyperthyroidism and lower urinary tract function.
