27y/o Caucasian female ADAF for 30 wk ROB G2 P1. Hx pre-eclampsia, bedrest and delivery baby girl at 35wks wt 5lbs 6 years ago. Current pregnancy was progressing normally except hypokalemic on oral replacement therapy and dietary changes. Today she presents with 15lb weight gain since last ROB visit, elevated BP 150s/110s but HR at her baseline (not tachycardic/still working on the floor and short staffed prior to appt) and complaints of heart burn. BP repeat manual no real improvement; fundal height consistent with dates, FHTs 150s, good fetal movement but patient reports some DOE. CMP ordered to f/u hypokalemia. Results showed continued hypokalemia (slightly improved) and new hypomagnesemia. WHNP consulted with OB MD and patient to start po magnesium supplementation slo-mag which was not available at MTF so civilian prescription given to patient. Patient now considered high risk OB and all future care must be scheduled with MD. Patient reported to provider later in the day that SOB worsening. CXR ordered and results WNL. OB MD consulted with MFM at another facility (not NNMC) and he recommended referral to MFM but order further blood (CBC, full chem. panel, LFTs) and urine electrolytes prior to MFM appt. Her urine electrolytes returned abnormal. Later that week patient had appt with MFM and was placed on bed rest at home with frequent provider appts. Patient’s previous OB records not available (civilian provider) and patient had consulted with OB provider prior to attempting this pregnancy because she was concerned pre-eclampsia and preterm delivery could occur again. She was told there would be a chance but not likely. MFM’s differential diagnoses include Gittelman’s syndrome and nephrogenic diabetes insipidus. Needless to say this patient's stress level was elevated from this point forward and she was very concerned about the well being of her unborn child. Luckily she has a strong support network but her family does not live nearby and she now had to drive much further for her OB care. I do not know if she has received a definitive diagnosis yet.
Gittelman’s syndrome (Orphanet Journal of Rare Diseases, 2008)
Gitelman syndrome (GS), also referred to as familial hypokalemia-hypomagnesemia, is characterized by hypokalemic metabolic alkalosis in combination with significant hypomagnesemia and low urinary calcium excretion. The prevalence is estimated at approximately 1:40,000 and accordingly, the prevalence of heterozygotes is approximately 1% in Caucasian populations, making it one of the most frequent inherited renal tubular disorders. In the majority of cases, symptoms do not appear before the age of six years and the disease is usually diagnosed during adolescence or adulthood. Remarkably, some patients are completely asymptomatic except for the appearance at adult age of chondrocalcinosis that causes swelling, local heat, and tenderness over the affected joints. Blood pressure is lower than that in the general population. In general, growth is normal but can be delayed in those GS patients with severe hypokalemia and hypomagnesemia.
GS is transmitted as an autosomal recessive trait. Mutations in the solute carrier family12, member 3 gene, SLC12A3, which encodes the thiazide-sensitive NaCl cotransporter (NCC), are found in the majority of GS patients. At present, more than 140 different NCC mutations throughout the whole protein have been identified. In a small minority of GS patients, mutations in the CLCNKB gene, encoding the chloride channel ClC-Kb have been identified.
Diagnosis is based on the clinical symptoms and biochemical abnormalities (hypokalemia, metabolic alkalosis, hypomagnesemia and hypocalciuria). Bartter syndrome (especially type III) is the most important genetic disorder to consider in the differential diagnosis of GS. Genetic counseling is important. Antenatal diagnosis for GS is technically feasible but not advised because of the good prognosis in the majority of patients.
Most asymptomatic patients with GS remain untreated and undergo ambulatory monitoring, once a year, generally by nephrologists. Lifelong supplementation of magnesium (magnesium-oxide and magnesium-sulfate) is recommended. Cardiac work-up should be offered to screen for risk factors of cardiac arrhythmias. All GS patients are encouraged to maintain a high-sodium and high potassium diet. In general, the long-term prognosis of GS is excellent.
http://www.ojrd.com/content/3/1/22 (longer more detailed version available at this website)
Nephrogenic diabetes insipidus (Nephrogenic diabetes insipidus foundation website, 2010) occurs when the kidney tubules do not respond to a chemical in the body called antidiuretic hormone (ADHADH), also called vasopressin. ADH normally tells the kidneys to make the urine more concentrated. As a result of the defect, the kidneys release an excessive amount of water into the urine, producing a large quantity of very dilute urine. This makes you produce large amounts of urine. Nephrogenic diabetes insipidus is rare. Congenital diabetes insipidus is present at birth as a result of an inherited defect that usually affects men, although women can pass the gene on to their children.
Most commonly, nephrogenic diabetes insipidus develops because of other reasons. This is called an acquired disorder. Factors that can trigger the acquired form of this condition include:
· Blockage in the urinary tract
· High calcium levels
· Low potassium levels
· Use of certain drugs (lithium, demeclocycline, amphotericin B)
http://www.ndif.org/public/pages/1-Introduction (more detailed information)
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