Essay Example on Alkaptonuria: Skin Discoloration, Urine Discoloration, Ochronosis

Introduction

Alkaptonuria is an uncommon autosomal recessive disorder of tyrosine and phenylalanine metabolism resulting from insufficient 1,2-dioxygenase activity and homogentisate, which causes a collection of huge quantities of homogentisic acid. Oxidation and polymerization of this acid result in deposits in the joints, cartilages, tissues, and blood, where an individual gets bluish-black skin pigmentation, which entails ochronosis. Also, discoloration of urine is a common symptom. Here, we present a case of alkaptonuric ochronosis with low trauma fracture of the left femoral neck.

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Case Report

A 79-year-old female presented with complaints of severe pain localized in the groin experienced for two days. The onset and progression of this pain were gradual, non-radiating, aggravated by rotation, or putting weight on the hip but lessened by rest. Her medical history entails undergoing numerous lithotripsy to treat kidney stones and experiences back pains due to the surgical procedures done on her spine. The parents were not consanguineous. Also, her degenerative arthritis has harmed her knees and hips such that her right hip was completely replaced five years ago. She made this decision due to the failure of the decline of the pain and limitation in movements after using physiotherapy and non-steroidal anti-inflammatory medication. A radiological examination conducted then showed that she had alkaptonuria. She also had cervical cancer, mild asthma, and hypothyroidism in her medical history. A year later, she went through standard vascular surgery for carotid endarterectomy with bovine pericardial patch angioplasty under general anesthesia, with neurologic surveillance being cerebral oximetry (Hernandez et al., 2018). She was put on statin and 81mg aspirin medication on the first postoperative day upon discharge from the theatre.

Statin drugs are vital in lessening the blood cholesterol levels as they restrict the conversion of 3-hydroxy-3-methylglutaryl coenzyme A (HMGC) into mevalonate by the enzyme HMGCR. They lower the rate of a person getting cardiovascular-related ailments, and they may cause myalgia where a person experiences general weakness, tenderness, or aches in their muscles. Aspirin was vital in preventing the occurrence of blood clots by making the blood thinner as well as relieving pain. There were no notable complications that emanated from the surgical procedures. She denied the intake of alcohol and stated that she did not have allergic reactions to any drugs. Other medications she used before undergoing surgery were albuterol, levothyroxine, and meperidine. Levothyroxine augments the production of hormones by the thyroid gland, which is essential in controlling the metabolic and energy requirements of the body hence treating hypothyroidism (Schneider & Reiners, 2003). Also, it lessens the chances of one contracting goiter as surgery or cancer causes the imbalance of the said hormone. Albuterol aided in treating asthma by relaxing the muscles in the lugs airways to allow passage of more oxygen and lower the cases of shortness of breath. Meperidine was used to lessen the severe pain brought forth by cancer.

Physical examination revealed that she had black colored spots on the lateral side of the cornea, the medial, and the sclera of the eyes, in the temporal and nasal areas. Also, there was a notable black discoloration of the skin on the cartilage of pinna, the dorsum of her two hands, and the face. There was no evidence of local tenderness of the black pigments. Besides, she complained of deep and bony pain and hardness of her left leg, which appears shortened compared to the right leg when it is held in abduction and external rotation. Palpation of the trochanter reveals a local bony tenderness, and it has swollen. Thus, plain radiography done on the anteroposterior view of the pelvis and the lateral view of the hip indicated that she sustained a stress fracture of the left femoral neck, which necessitated surgical treatment (Hayat & Varacallo, 2019). Dual-energy X-ray absorptiometry indicated that the femoral neck had a bone mineral density T score of -3.02, which is below -2.5 hence putting the woman at a high risk of having a fracture. X-ray around the spine region indicated multilevel intervertebral disc calcification, which led to making the provisional diagnosis of ochronosis that was confirmed by a positive urine test for HGA. The woman received symptomatic treatment with analgesics, vitamin C tablets 500mg, and physiotherapy.

Discussion

Alkaptonuria is an uncommon autosomal recessive congenital metabolic disorder mainly caused by a gene mutation. The process of gene mutation lowers the levels of hepatic enzyme homogentisate 1,2-dioxygenase (HGO), which plays the role of converting homogentisic acid (HGA) into maleyl acetoacetic acid thus increasing the accumulation of HGA and benzoquinone which occurs after oxidation of HGA. The deposits usually put an individual at risk of tissue injury as they accumulate there as well as in the joints. Also, such a collection of HGA facilitates the gradual onset of ochronosis that causes the black pigmentation of the skin, cartilages, and sclera, as well as causing homogentisic aciduria at birth where oxidation or alkalization of urine causes it to blacken (Dave et al., 2001). The addition of sodium hydroxide to the urine caused it to turn into black color, which meant that the patient had accumulated HGA. Besides, the collection of HGA causes the tissues to turn slate blue, and it results in an inflammatory reaction that kills chondrocytes and causes the calcification of the intervertebral disc. The increased pigmentation in the skin and external body parts of the patient indicates the continuous spread and staining of the cartilage and other body tissues.

Arthritis is a disabling effect on the condition of alkaptonuric ochronosis, and it usually happens to individuals as their age advances. It manifests itself like inflammatory or crystalline arthritis, but it is a progressive and degenerative type of arthritis. It affects the knees, hips, and intervertebral discs, and it is associated with stiff back pain as depicted by the woman. Besides, the woman had suffered a severe internal carotid artery stenosis as it had black pigmentation in the intima upon dissection (Hernandez et al., 2018). More so, the previous hip replacement procedure that she underwent increased her risk of experiencing the fracture. Also, the fracture manifested the degenerative changes that usually occur in the joints and the spine due to arthritis.

Moreover, the prolonged use of levothyroxine to treat hypothyroidism may have increased the susceptibility of the woman to this fracture due to her osteoporosis status. The medicine aims at increasing the thyroid hormone in the body because it is in low quantities, but it increases the rate of bone loss in the woman. The osteoblasts cannot replace the bone loss with the required speed. The medication has the capability of reducing bone mineral density, especially in the femur and spine regions in postmenopausal women (Schneider & Reiners, 2003). The reduction in the femoral neck bone mineral density of the woman is attributable to the increased calcification of the intervertebral disc. Homogentisic acid can restrict the formation of intracellular hydroxylysine, which results in a reduction in the inter-molecular connections, which are fundamental in ensuring the structural functioning of the newly created collagen.

The treatment accorded to the woman was symptom relief, which includes analgesics and physiotherapy. Such a combination of treatment is crucial in preventing further disability. Analgesics are vital in mitigating the pain after the operation, while physiotherapy aids in restoring the leg to normalcy by facilitating the connection and strengthening at the neck region of the bone. The use of vitamin C ensures the provision of ascorbic acid, which is a mild antioxidant which hinders the conversion of homogentisate to a polymer that ends up deposited in the tissues (Dave et al., 2001). Besides, she should observe her diet by avoiding foodstuffs that are rich in tyrosine and phenylalanine to lower the rate of excretion of HGA. Use of Nitisinone has both the biochemical efficacy and high tolerability that would contribute to a reduction in the production and excretion of HGA through urine.

References

Dave, U. P., Udani, V., Fernando, J., Zhang, C., & Matsumoto, I. (2001). Chemical diagnosis of congenital metabolic disorders by gas chromatography/mass spectrometry (GC/MS) in India. International Journal of Human Genetics, 1(3), 211-217. https://doi.org/10.1080/09723757.2001.11885761

Hayat, Z., & Varacallo, M. (2019). Surgical management of femoral neck fractures. In StatPearls [Internet]. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK538236/

Hernandez, N. M., Chalmers, B. P., Perry, K. I., Berry, D. J., Yuan, B. J., & Abdel, M. P. (2018). Total hip arthroplasty after in situ fixation of minimally displaced femoral neck fractures in elderly patients. The Journal of arthroplasty, 33(1), 144-148. https://doi.org/10.1016/j.arth.2017.07.035

Schneider, R., & Reiners, C. (2003). The effect of levothyroxine therapy on bone mineral density: A systematic review of the literature. Experimental and clinical endocrinology & diabetes, 111(08), 455-470. DOI: 10.1055/s-2003-44704