Cystic kidney disease

Cystic kidney disease refers to a wide range of hereditary, developmental, and acquired conditions.[1] With the inclusion of neoplasms with cystic changes, over 40 classifications and subtypes have been identified. Depending on the disease classification, the presentation of disease may be from birth, or much later into adult life. Cystic disease may involve one or both kidneys and may or may not occur in the presence of other anomalies.[1] A higher incidence of cystic kidney disease is found in the male population and prevalence increases with age. Renal cysts have been reported in more than 50% of patients over the age of 50.[2] Typically, cysts grow up to 2.88 mm annually and cause related pain and/or hemorrhage.[2]

Cystic kidney disease
Renal cyst
SpecialtyMedical genetics 

Of the cystic kidney diseases, the most common is Polycystic kidney disease; having two prevalent sub-types: autosomal recessive and autosomal dominant polycystic kidney disease.[1] Autosomal Recessive Polycystic Kidney Disease (ARPKD) is primarily diagnosed in infants and young children. Autosomal dominant polycystic kidney disease (ADPKD) is most often diagnosed in adulthood.[1]

Another example of cystic kidney disease is Medullary sponge kidney.

Types

More Cystic Kidney Diseases

Cystic kidney disease refers to various conditions relating to the formation of cystic in the kidney or kidneys. The most common subset of cystic kidney disease is polycystic kidney disease (PKD). Polycystic kidney disease is a genetic anomaly, PKD has two subsets, autosomal recessive polycystic kidney disease (ARPKD) and autosomal dominant polycystic kidney disease (ADPKD). The causation of cystic kidney disease can be genetic, developmental, cysts with systemic disease association can be acquired, or malignant. Examples of acquired cystic kidney disease include simple cysts, acquired the renal disease, and medullary sponge kidney (MSK). Other types of genetic cystic kidney disease are juvenile nephronophthisis (JNPHP), medullary cystic kidney disease (MCKD), and glomerulocystic kidney disease (GCKD).

Polycystic Kidney Disease

PKD causes numerous cysts to grow in the kidneys, the cysts are filled with fluid and if they grow excessively this will lead to kidney damage. Mutations in genes PKD1 and PKD2 are responsible for autosomal dominant polycystic kidney disease (ADPKD). Those genes encode for polycystic proteins, mutations regarding those genes are inherited are responsible for the disorders of autosomal recessive or dominant cystic kidney disease. In the United States, more than half of million people have PKD, making it the fourth leading cause of kidney failure. PKD affects all races and genders equally. People with PKD have a possibility of developing cysts in other organs like in the liver, pancreas, sleep, ovaries, and large bowel. Usually, a cyst in those organs does not impose a problem. Half of the patients have no manifestation of symptoms, but symptoms may include: hematuria, back or abdominal pain, or can develop hypertension. The disease is usually manifested before age 30, but 45% develop renal failure by age 60.

Cause

The prefer formation site for the cysts is the renal tubule segments, after they grow into a few millimeters they detach from the parent tubule, induced by excessive proliferation of tubular epithelium or excessive fluid secretions.

Diagnosis

Methods of diagnosis include ultrasounds, CT scan, and MRI scan. The least inexpensive, non-invasive, and most reliable method of diagnosis is an ultrasound. Ultrasounds are the best method for diagnosis but might not detect the smaller cysts in the kidneys. CT scans and MRI scans are able to capture the smaller cysts that cannot be see in an ultrasound, but normal CT scans and MRI scans would only be used as a diagnostic tool for someone at high risk. MRI are used to monitor the development of the cysts and growth of kidneys. Genetic test can be applicable to those who have family history of PKD. Genetic testing is very expensive and sometimes it fails to detect PKD in 15% of people who have it.

Antenatal scans

Many forms of cystic kidney disease can be detected in children prior to birth. Abnormalities which only affect one kidney are unlikely to cause a problem with the healthy arrival of a baby. Abnormalities which affect both kidneys can have an effect on the baby's amniotic fluid volume which can in turn lead to problems with lung development. Some forms of obstruction can be very hard to differentiate from cystic renal disease on early scans.

  • Multicystic dysplastic kidney - affects only one side; the other kidney is usually healthy.
  • Cystic dysplasia - can affect one or both kidneys
  • Autosomal recessive polycystic kidney disease
  • Autosomal dominant polycystic kidney disease
  • Posterior urethral valves - easily mistaken for cystic renal disease on early scans; appearances are due to obstruction not cysts
  • High grade vesico-ureteric reflux - easily mistaken for cystic renal disease on early scans
  • Pelvi-ureteric junction obstruction - easily mistaken for cystic renal disease on early scans

Treatment

Treatment is essential to manage the disease and symptoms, therefore to avoid complications. Some of the treatment options include pain medication (except ibuprofen since it worsens kidney disease), low protein and sodium diet, diuretics, antibiotics to treat UTIs, or surgery to drain cysts. In advance, cystic kidney disease renal transplant or dialysis might be necessary.

Prognosis

By late 70s, almost 50-75% of patients with CKD require dialysis or a kidney transplant. If the patient requires a kidney transplant, kidneys are usually not taken from children due to this disease being hereditary. The cysts and kidney volume is a predictor of the progression of CKD and end-stage renal disease. Should be noted that PKD does not increase the risk for renal cancer, but if renal cancer is developed it is mostly to be bilateral. The most probable cause of death is heart disease, ruptured cerebral aneurysm, or disseminated infection. Some factors that can affect life expectancy are mutated gene type, gender, the age of onset, high blood pressure, proteinuria, hematuria, UTI, hormones, pregnancies, and size of cysts. If risk factors are controlled and the disease is stabilized then the patient's life expectancy can be prolonged greatly.

References

[3] [4] [5] [6] [7] [8]

  1. Bisceglia, M; et al. (2007). "Renal cystic diseases: a review". Advanced Anatomic Pathology (13): 26–56.
  2. Campbell, SC; Novick AC; Bukowski RM (2007). Campbell-Walsh Urology (ed.). Neoplasms of the upper urinary tract (9 ed.). Philadelphia: Saunders. pp. 1575–1582.
  3. "Average Life Expectancy For People With PKD." PKD Clinic, www.pkdclinic.org/pkd-prognosis/342.html
  4. "Autosomal Dominant Polycystic Kidney Disease (ADPKD) - Genitourinary Disorders." Merck Manuals Professional Edition
  5. "Polycystic Kidney Disease." Mayo Clinic, Mayo Foundation for Medical Education and Research, 6 Mar. 2018
  6. "Polycystic Kidney Disease." The National Kidney Foundation, 3 Feb. 2017
  7. "Polycystic Kidney Disease." American Kidney Fund, www.kidneyfund.org/kidney-disease/other-kidney-conditions/polycystic-kidney-disease.html#what_causes_polycystic_kidney_disease_pkd.
  8. "Cystic Diseases of the Kidney Treatment & Management." Cystic Diseases of the Kidney Treatment & Management: Medical Care, Surgical Care, 28 Mar. 2017
Classification
External resources
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